Oklahoma! Oh, what a beautiful way to start off Lone Star Performing Arts's 21st season. Oklahoma! follows the sweet story of a cowboy and a farm girl who fall in love, and the no-good who tries to muck up their good time. You already know the songs: Besides the title tune, there's "Oh, What a Beautiful Mornin'," "The Surrey with the Fringe on Top" and "People Will Say We're in Love." Opens at 8 p.m. tonight. Performances continue every night but Sunday through June 28. Galveston Island Outdoor Musicals, FM 3005 at 13 Mile Road, Galveston, (800) 54-SHOWS. $17-$29; $7.50$14.50, children.