He was a black prosecutor from rural Alabama who wanted to learn how to unseat a white probate judge back home.

His county, Lowndes, was 70 percent black, but many young blacks had moved away to find jobs. Others were unemployed and believed it was useless to register.

Nathaniel Walker came to find out how to change their minds. "If I show them I won't be like the tyrant who's in there now, I figure they'll come out," he said. But "I need a few pointers."

Walker was among 200 aspiring candidates, budding political strategists, local labor leaders and civil rights activists who packed the yellow brick Masonic Temple here for a two-day prep school on waging political war. Schoolteachers, retired farmers, mechanics and housewives came in for free advice from political veterans.

"If we don't get briefed and tighten up, some people with a little hand greasin' will steal our hope and we'll get sold out again," said John Peyton, 69, a black farmer from Lawrence County, Miss., which is 40 percent black and has no black elected officials.

In Mississippi, for example, some 2,500 elective offices, from city council to county supervisors, will be up for grabs in 1983. Rep. John Conyers Jr. (D-Mich.), who organized the Parker-Coltrane Political Action Committee that funded the candidate-training seminars here, figures to teach blacks how to win their share.

"Blacks hold the balance of power, if not absolute electoral majorities, in scores of Deep South congressional districts," he said. "Yet, only two of the 18 black members of Congress come from the region."

None come from Mississippi, which became the fourth southern state last week to have its congressional redistricting plan rejected by the Justice Department for violating the 1965 Voting Rights Act. The rejected plan would have cut the heavily black Delta region into three chunks, diluting black voting strength.

Yet, the state presents a model for black political aspirations. Some 36 percent of Mississippians are black, most of them clustered in the Delta. There are more than 400 black elected officials, almost 10 percent of the state's public servants. Seventeen of 174 legislators are black. No state has more black officials.

But Robert Walker, 38, field director for the state NAACP who taught one seminar, says it only "looks good on the surface. Blacks have achieved only symbolic power. Black legislators can do little more than ask for a roll-call vote."

Conyers, following the lead of successful conservative PACs, has organized a liberal counterpart to unite blacks and labor behind progressive candidates, naming it after celebrated jazz saxophonists Charlie Parker and John Coltrane. The PAC, seeded with money from a recent Nancy Wilson benefit concert, graduated its first class here Saturday.

"It's like a rebirth of the '60s," said Bettye Hunt, 61, the first black woman since Reconstruction to win a seat on the Hinds County, Miss., election commission. She said past political campaigns were waged more on chutzpah than expertise. "We're getting down-to-earth expertise in every field."

There were workshops on demographics, targeting, candidate selection, filing procedures, campaign strategy and organization, fund-raising and coordination of volunteers and how to get out the vote.

One state legislator urged candidates to "wear conservative clothes unless you're going to a picnic," shave all beards--"beards turn some people off"--and project a "moderate" image.

Radicals should don three-piece suits; the goal is to "count the vote," said Credell Calhoun, a black Mississippi legislator.

Getting elected is as much sociology as politics, candidates were told. Often, office-seekers have got to grin and bear it, especially women candidates, counseled Mary Coleman, a Jackson State University professor. "Your consciousness might tell you, 'These folks are bastards.' But your savvy tells you, 'I've got to deal with the bastards to get elected.' You've got to play a role" to gain acceptance from a wide range of people."

In back rooms at the lodge, there was much kibitzing and plotting how to bolster friends and oust enemies. Wendell Paris, 37, a member of the Sumter County, Ala., school board, came gunning for his congressman, Rep. Richard C. Shelby, a "boll weevil" Democrat.

Before it was over, Paris had solicited promises of money and union support for his anti-Shelby campaign from the A. Philip Randolph Institute, a black-labor coalition that helps finance such efforts. "Shelby's district is 36 percent black, so we figure we need a progressive white candidate," he said. "I'm looking for tips on coalition-building . . . . "

Such plans were salted with bitter fallout from Reagan budget cutbacks. Blacks have felt the ax cut deep in entitlement programs, and Alabama has one of the highest unemployment rates of any state in the country. Some black leaders preached a new unity, labeling Reagan "the best friend the civil rights movement ever had." Others saw the PAC as evidence of a new willingness among blacks to align with labor's money and manpower.