Only those who've suffered it have any business laughing at poverty.

That's why Whoopi Goldberg, who was a welfare mother two years ago and will make about $1 million for her next movie, has become the heartbeat of "Comic Relief," the Home Box Office all-star benefit show to aid America's poor.

Along with Billy Crystal and Robin Williams, she will cohost the live three- hour production Saturday night at 9 from the Universal Amphitheater in Los Angeles.

"All the stuff I do has been for stuff I've experienced or been close to," said Goldberg. "I've been in the street. I don't understand how people are living in dumpsters . . . how we can cut budgets (for the poor). There's more than enough opportunity here."

Whoopi Goldberg should know. Hers is one of those show business stories that seemingly was scripted in Hollywood itself, the complicated odyssey of a woman long on energy and talent but short on breaks who suddenly is discovered by the right people at the right time.

Two years ago, the only person who knew her name beyond a relatively small circle of friends was producer Mike Nichols. He put her on Broadway, a one- woman show on Broadway. Since then she's had an awesome impact on every major entertainment medium in America. She's done a TV special for HBO and recorded a Grammy-winning album. And this week she's up for the Academy Award for her much-acclaimed performance as Celie in the film version of Alice Walker's "The Color Purple."

With the Oscar ceremonies to be telecast Monday night, it is a week of high symbolism for Goldberg: One evening measures how far she's come and the other reminds her of where she's been. "I'm very excited," she said. What would she wear to the Oscar ceremonies? She wasn't sure, but jeans and a leather jacket weren't out of the question.

Whoopi Goldberg was born in the Chelsea section of New York and started training for the stage at the Helen Rubenstein Children's Theater at age 8. Early work included small parts in "Pippin," "Hair" and "Jesus Christ Superstar."

She moved to California and, in 1974, was a founding member of the San Diego Repertory Company. She starred in the company's productions of "Mother Courage" and a Marsha Norman play, "Getting Out." At the same time, she performed with an improvisational company appropriately called Spontaneous Combustion.

She moved north and joined Berkeley's Blake Street Hawkeyes. It was there that she began assembling the menagerie of comedic characters that became the basis for "The Spook Show," which she performed in San Francisco and took on the road. Match met gasoline when Nichols caught her act at Manhattan's Dance Theatre Workshop.

Along the way, Goldberg was married briefly and has a daughter. She recalls, with some difficulty, being a welfare mother in San Diego two years ago, and carries with her a sensitivity to the down and out that readily surfaced when she discussed her role in "Comic Relief."

"I've been real close" to the homeless, she said, recalling that there were times she did not have a place to live and "stayed on the good graces of friends."

"I don't want to get real into it," she said of those days. "It would upset my mom."

Goldberg, whose comedy routines are sometimes outrageous in tone and vocabulary, was precise and restrained when asked if the Reagan administration was a villainous one from the standpoint of the poor. "I see it as a forgetful administration," she said. "A very unaware administration. They're not carrying on the way a group responsible for the country should."

She also senses a waning sensitivity to the poor as the nation's economy slowly improves. Looking to Detroit for an example, she noted that "when the auto industry was hurt there was a camaraderie that developed" as people who knew what it was to have jobs suddenly found themselves in the same line with people they had frowned upon. "Now the industry is back," she said, and the social distance between workers and nonworkers has grown again. "All of (the unemployed) are not junkies and bums," she said.

"I can't change the world," she added. "This show is the best I can do."

The show should be something. HBO, a subscription television service, announced recently that it was permitting all of its affiliates to carry the benefit as part of their basic, no-extra-fee service. According to HBO, that creates a potential audience of 39 million cable subscribers.

In discussing the show, Goldberg, Crystal and Williams refused to say how much they hoped to raise through donations. A formidable assortment of comedians will appear, ranging from veterans such as Steve Allen and Sid Caesar to newcomers like Michael J. Fox and Michael Keaton. Stand-up routines and sketches are expected to be the order of the evening.

The show is the brainchild of Bob Zmuda, a screenwriter and producer who previously organized an American Cancer Society benefit honoring the late Andy Kaufman.

Whoopi Goldberg puts considerable stock in documents. She giggles about the secrets contained on her California drivers license -- like her real name, Caryn Johnson, and her real age, 30, rather than the widely published 35 ("I had to lie about my age to get some jobs"). And she still has her MediCal card from the lean days in San Diego, framed and hung at home.

Along the way to stardom she did an assortment of jobs, like working as a bricklayer, a bank teller and a cosmetician at a morgue. But People magazine reported that she made $250,000 for playing Celie and will receive $1 million for whatever movie she does next. So the ays of making up corpses are probably over.

But perhaps because the hard times were so recent, she speaks of joblessness and homelessness as if they were waiting just around the corner for anyone and everyone. For some, they were.

The steelworkers and carmakers whose industries and companies sagged or collapsed were just regular people, shirtsleeve Americans who were suddenly out of work, she said.

"They are the people -- the we-the- people in the Constitution," she said. "Maybe I'm naive, but I can't see why it happens. So I've got to add my voice."