husband's position and a determination the White House will be "a place that people can turn to for help," Rosalynn Carter set out yesterday to focus attention on two fields of particular concerned to her - the elderly and the mentally disabled - and the problems unique to each.

It was her first major move toward keeping some campaign promises of her own.

In a mid-morning address to 1,100 delegates to the 27th Annual Conference of the National Council on Aging, the First Lady announced a May 10 "roundtable" discussion" on the aging at the White House, which she called "a first step" in her campaign pledge "to help personally."

Reading excerpts from four of the 3,060 letters she receives weekly on such subjects, she said their elderly authors represented old people everywhere who "struggle to stay warm, have decent clothes, decent clothes food to eat, try to pay their bills and not be a burden to anybody."

She told of inviting representatives and experts from 17 lay and professional groups "to discuss the problems and also to seek solutions. I know there are many programs already for the elderly but the concern I have is that these programs do not reach the people they are supposed to reach."

She said she will seek greater coordination through "an agenda for channeling information about valid programs. I am determined that the White House will be a place that people can turn to for help. I am determined that the White House will be open and available for help."

Later, at the Department of Health, Education and Welfare, she participated in a meeting of the President's Committee on Mental Retardation, exhorting its 25 members to provide specific recommendations that could provide a basis for legislation her husband may propose.

She wanted recommendations on how to help families of the mentally retarded through programs similar to those offered families of alcoholics. She called for suggestions on training professionals to work with those families, ways to dispel the stigma of retardation and illness, and ideas on educating the public to "understanding and acceptance."

She had a word of advice, while she was at it. Knowing from experience that "if you give Jimmy specific, brief, understandable recommendations," the likelihood of results was better than if he is presented "reams" of text.

She wanted some answers herself, she indicated during presentations by heads of the committee's seven task forces.

"It distresses me to see funds cut," she told Dr. Cecil B. Jacobson, head of research and prevention. "I don't think we had enough in the first place."

"I don't think that's the major problem," Jacobson replied. "I think the major problem is in applying what we already know."

Eunice Kennedy Shriver, a special guest at the session, said later that Rosalynn Carter had made "a good point but she didn't get a very good answer. In fact, less than $2 million, goes into research on prematurity . . . Research and reproductive biology are important for prevention (of mental retardation) but nobody is really very interested."

HEW Secretary Joseph A. Califano Jr., however, was hopeful that "the next few years are going to mean to the handicapped and retarded some turmoil but the kind of progress the blacks made in 1960."

As for Rosalynn Carter, Califano, who is automatically chairman of the committee, which was established in 1966, was equally optimistic.

"It may be the best thing that's happened in this area isn't the direct election of Jimmy Carter," he said, "but the indirect election of Rosalynn Carter."