Gesturing to the entertainment trailers, the harried organizers moving in and out of the restricted area and the workmen hauling a piano across the grass, Damien Atkins said, "This is more my kind of thing -- middle management -- you know, behind the scenes, not out in front."

But that was yesterday morning, with a rehearsal for the "Celebration of Citizenship" well under way on the West Lawn of the Capitol.

Today, when he steps up to a microphone and introduces President Reagan to a nation honoring the bicentennial of its Constitution, middle management obscurity will temporarily elude the senior at Banneker High School in Northwest Washington.

Atkins was selected to represent America's youth in today's ceremony after being nominated by his high school and auditioning with other District students before a panel of educators at the office of the superintendent of D.C. schools.

During the half-hour official ceremony marking the anniversary, Atkins will deliver a brief speech about citizenship, introduce the president and share the podium with former chief justice Warren E. Burger, House Speaker Jim Wright (D-Tex.), Senate Majority Leader Robert C. Byrd (D-W.Va.) and Chief Justice William H. Rehnquist among others.

"I don't have butterflies, per se," Atkins said yesterday as he waited for his turn in the rehearsal lineup. "It's more or less an enlightenment of what's going on. I didn't know it was going to be this big a deal.

"It's kind of thrilling, because it is living history. I get to meet someone who is going to be in the history books," Atkins said of Reagan. "All these people in the program -- their names will be in the Archives. When I go to the Archives to do a research paper, I just see these names and I just write them down. They're nobody to me."

But after today, those history-book names will have a new meaning. Atkins will have crossed paths with the kind of history that creeps into high school term papers.

His brush with history began over the summer when the Commission of the Bicentennial, looking for a District student with a record of academic and civic achievement to introduce the president at today's ceremony on the West Front steps of the Capitol, asked the principals of public schools to nominate outstanding students.

Banneker's assistant principal, Robert Steptoe, looked over his roster of students and selected Atkins, a member of the National Honor Society, the Model United Nations Club and the Student Congress Delegation. Atkins, who moved to Washington two years ago, was born in California and has lived, because of his father's career as a Foreign Service officer, in Panama City and Quito, Ecuador.

According to Steptoe, Atkins stands out as an "intelligent . . . articulate . . . unflappable fellow. I didn't think it would be the kind of thing that would intimidate him."

Last month the eight students nominated by their principals auditioned at the superintendent's office.

Cecile Middleton, executive assistant to the office of deputy superintendent, said that Atkins particularly impressed the panel of judges because unlike the other students who had received instructions to prepare speeches, he arrived with no idea that he was about to demonstrate his public speaking skills, to say nothing of competing to participate in a nationally televised ceremony featuring the president.

"He quickly got his thoughts together," Middleton said, "and did a fantastic job delivering a speech that was strictly off the cuff."

His father, Edmund Atkins, said when he dropped his son off at the superintendent's office that neither of them realized it was an audition. "If I'd known it was for this, I would have waited." Edmund Atkins said yesterday.

"The next thing you know," Damien Atkins said, "I went down there, made the speech, and a letter arrived in the mail several days later: 'We've selected you.' "

So until a television crew arrived to interview him at his school near Howard University, until the rehearsal approached and until all sorts of famous names started appearing on the horizon, it was no big deal. Certainly nothing to undermine his unflappable demeanor.

Even yesterday, as he began to recognize "the magnitude" of the event, a handful of other worries competed for his attention: Would he get a ticket on his illegally parked car? Would he win the upcoming election for vice president of the District chapter of Jack and Jill of America? Could he reschedule his senior pictures session? And will he get into Stanford University?

Atkins mused that "Andy Warhol said everyone is famous for 15 minutes. I guess mine will be over by today."