"IT'S STRANGE, this is one of the biggest nights of my life, and everything's out of my control," says Joe Palka, the night before his first play, "The Last Stand of the Polish Sharpshooters," is to open at Source Theatre as part of its ninth annual Washington Theatre Festival. "I don't have a script to memorize, I don't have tech cues to remember . . . It's my baby, but it's on its own." Palka is a former WMAL radio personality and part-time actor (Gross National Product, Washington Theatre Wing). "When I was working for WMAL, I'd do character voices, and we'd create little sketches for them. I figured rather than write 100 different radio bits, why not write a 100-page script? Something that would have a bit of permanence -- the significance remains to be seen," Palka says. The seed for his 10-character comedy was planted one night when Palka was doing a late-night radio talk show in the heavily Polish town of Erie, Pa. A call came in from a listener who insisted that Palka In a waning industrial town, the remaining members of the Polish Sharpshooters decide to create a float for the annual Polonaise Day parade, which is themed "Famous Polish Americans." There's a dispute over whether Bobby Vinton or Stan "The Man" Musial is more famous. Then somebody suggests Pope John Paul II (who is not even American, but that's another issue). Like the characters in the play who put up their own money to create the float that revitalizes their fading club, the cast of "Last Stand" -- all volunteers -- created their own costumes (the real Sharpshooters sent their own bowling shirts, complete with their embroidered names on the breast pockets), helped build the set and locate props (director Karen Berman even located a baseball autographed by Musial), and worked long, odd hours in the hope that somebody will see the play and perhaps give it a second production. "That's the thing about this Theatre Festival," Palka says. "I don't get paid, but then, this is my dream come true. Theater is very generous by nature." "The Last Stand of the Polish Sharpshooters" continues through Saturday at Source Theatre. Call 462-1073 for further Festival information. ANOTHER STERLING example of do-it-yourself theater is Bethesda's Wildwood Summer Theatre, a youth theater troupe which marks its 25th anniversary this month with a production of the Studs Terkel-adapted musical "Working" playing at Walt Whitman High School through August 12. "The Wildwood Summer Theater was formed as an experiment. We wanted to find out if students, unassisted by adults, could competently present to the public an elaborate, full scale musical production." That's from the program of Wildwood's first production, "Bye Bye Birdie," in 1964. After Walter Johnson High School decided not to sponsor any more Drama Club summer musical productions, the students decided to do it for themselves. They found rehearsal space, built the set in a driveway, financed the production and rented the high school's gym for performances. The troupe went on to produce musicals from the 1965's "The Fantastiks" to last year's "Merrily We Roll Along." By the way, Jonathan Hadary, one of the more famous of the original Wildwood bunch, will be back in town playing Herbie in the revival of "Gypsy" at the Kennedy Center beginning August 10. Call 966-7286 for "Working" reservations. NEW YORK CITY has its Pan-Asian Repertory Theatre, Los Angeles has its East-West Players, San Francisco has its Asian-American Theatre Company. But aside from the occasional imported troupe at the Kennedy Center, Washington, which also has a large Asian population, sees precious little theatrical representation of that culturally diverse community. The D.C.-based Asian-American Arts & Media organization, which presents a film festival every fall, is looking into changing this state of affairs. "There is certainly a huge Asian community here, and I see a real need for an Asian-American theater," says the cultural organization's spokesman David Yang, who formerly worked as an actor with San Francisco's Asian-American Theatre Company. "I think the time has come -- it's just a matter of generating some interest." Yang says he'd like to mount a "small scale production" this fall or winter, and hopes to develop a company devoted to both Asian-American and translated contemporary Asian works. Interested theater artists should call 244-3415. "SISTER Mary Ignatius" has moved out of Source Theatre to make way for the ninth annual Washington Theatre Festival, but she's alive and well. The long-running Source/Scena co-production of Christopher Durang's Catholic comedy had an SRO run at the Montgomery Playhouse recently; it plays the Reston Community Center, 2310 Colts Neck Road, at 8:30 this Friday and Saturday and 3 Sunday. (Call 476-1111.) Scena director Robert McNamara says the "Sister Mary" company has raised $14,000 toward taking the six actors (and 8-year-old actor Erik Buchanan's mom, too) to the 82-seat Moray Union House at the Edinburgh International Festival August 10; the troupe hopes to raise another $8,000 before then.