Outside this small town of 10,000 people, 30 miles south of Managua, a teen-aged Sandinista guerrilla with an M16 rifle slung casually over his shoulder stops all vehicles and motions to a crowd of peasants hovering on the side of a road.

"Dear comrade," he says with a smile, "would you mind driving a few of these people into the city? They are humble peasants and have no other way to get there."

Whether out of revolutionary solidarity or a recognition of authority, it is a request few turn down. The credo of Nicaragua these days is: You will be nice to each other, you will share for the good of all, and the Sandinistas are here to make certain you do.

For a town such as Diriamba, still gasping from the destruction of a war that ended little more than a week ago, there is hardly any choice.

Nearly everyone here is unemployed. For farm workers, there is little seed to plant and no fertilizer to nourish it. Diriamba's prewar industries - a rum distillery, a small plant that made plastic bags used to ship bananas, and a company that assembled purses for export - have been closed for months and lack supplies to start up again.

Many workers used to commute to industries in Managua, but most of those suffer from the same shortages or were looted or destroyed by bombing. In any case, public transport is still in disarrary and there is no gasoline.

Although energetic attempts have been made to clean up the adobe-lined streets, there is no hiding the bullet holes in most buildings. The Spanish-style town square is filled with rubble where the National Guard garrison stood and the five-story clock tower - Diriamba's one distinguishing landmark - has a hole as big as a man's fist where a tank shell went through it.

Diriamba was taken by the Sandinistas more than a month ago, about midway through their war with the National Guard. Surrounded by hostile Guard forces and cut off from supplies from the capital it has been, and largely continues to be, in the words of one of its civilian administrators, an autonomous state.

Like many Nicaraguan towns in similar situations, it has developed its own government under the local Sandinistas. The new federal government is still sorting out the country.

Although the Sandinistas stress that the situation here is only temporary, what they have done in Diriamba is indicative of the vast problems and changes now confronting Nicaragua.

There are two groups in authority in the town. One is the Sandinista staff chiefs, who appear to be in charge of everything from security to food distribution to propaganda. The other is a six-member civilian junta made up of local men nominated by the chiefs and voted into office at a city-wide meeting. The junta handles such administrative affairs as transportation, civil justice and planning.

Nadine Lacayo, usually addressed by her nom de guerre, Lucia, is 22. She wears a pistol in her belt and a black berret with a red stripe. She is the Sandinista political leader here and has been in Diriamba - first underground and now in an office in a requisitioned house - for two years.

Lacayo is the link between the Sandinista chiefs and the city's "popular organization," the five civil defense committees that were organized clandestinely during the war and now run health clinic, food distribution and security. Committee members are chosen by popular vote, with one delegate for each two-block area of approximately 50 families.

The committees are in charge of knowing everyone who lives in their zones, their needs, and to a certain extent their activities.

Lacayo also is in charge of the Sandinista National Liberation Front propaganda office. Mildred, 18, explained that its functions include publishing a single-page mimeographed newspaper.

"We also have a Sandinista band," Mildred said. "tand we hold public meetings to motivate people and to tell them about the revolution and our heroes and martyrs."

Food supplies are minimal. There is no rice and very little beans, the two staples of the Nicaraguan diet. Storekeepers and the traditional market stalls are free to sell whatever they can get their hands on, but there are few supplies apart from bananas and onions.

Commodity stores, primarily sugar and eggs, have been requisitioned by the Sandinistas and are rationed, as are medicines, through the civil defense committees. Gasoline is available only for official vehicles. Government workers are paid in food.

Each city zone also contains a Sandinista garrison in charge of security and public order. Its greatest concern right now, guerrilla commanders said, is trying to get guns out of the hands of youthful civilian militia who helped during the war but are now causing problems.

In a half-bombed building on the square, four of the civilian junta's six members met yesterday. Julio Rocha, an agronomist specializing in peasant development, leads the group.

"We realize the need to draw clear lines between the military and civilians here," Rocha said. "But we have been living in a war.We were most concerned with security, and things are just starting to settle down.

"But make no mistake. We are very clear about the social fruits of the revolution. Change is going to effect everyone here. Some people want it overnight, but we'll go slowly, it will come stage by stage."

"The business people are concerned," Rocha said, "but the peasants have the same concern. They want to know what's happening. Everyone wants to resolve the problems immediately. They want stability."

Both the junta and the political-military Sandinista chiefs stress that Diriamba's system is "provisional" - that some future form of government based on a federal program eventually will replace them.

For now, Diriamba's government seems a complementary marriage of basically conflicting ideologies that people strongly support in the aftermath of months of chaos.

Already, however, a number of private farms abandoned by owners who fled the country before and during the war have been at least temporarily taken over by peasants who have begun growing food.

As far as business is concerned, "we're hesitant about investing money to get going again," the owner of an electrical supply company said. "We don't know how much our currency is worth, or how much more in credit we can get. And the country is being ruled by decree; we want to wait until things are firmed up, until we have a constitution and real laws."

here, as in much of Nicaragua, people appear unsure and anxious about what will happen next. But those interviewed from various economic and political groups were uniformly happly that former president Anastasio Somoza and the National Guard are gone and the Sandinistas have won.

Even the poorest peasants wax poetic on this score.

"When I used to see the National Guard pass by my corner," said an old man sitting in the noontime shade, "it would make my hair stand up.

"For the future, no one knows," he said. But for the present, "you don't even have to ask. It's like we were all born again." CAPTION: Map, no caption, By Dave Cook - The Washington Post