For its spring musical last year, Chapel Hill High School staged an ambitious production of "Ragtime," a complex, sprawling work about the social forces buffeting America as the 19th century gave way to the 20th.It was a powerful experience and a valuable learning opportunity for the students in the cast of 65 and dozens more on the backstage crew. It also was exhausting."'Ragtime' was a heavy drama, and every day I went home feeling like I'd been emotionally battered," said Thomas Drago, who leads the school's theater department. "I think everybody involved felt that to some extent. So this year we decided to go in a different direction and do something light-hearted and fun, an all-out comedy. And it's been great. Now I go home every day laughing."CHHS will present the classic musical comedy "How to Succeed in Business Without Really Trying," Thursday through Saturday. The show at Chapel Hill High's Hanes Theater will be at 7:30 p.m. each day. With music and lyrics by Frank Loesser and book by Abe Burrows, Jack Weinstock and Willie Gilbert, the show was a commercial and critical hit when it opened on Broadway in 1961. The musical is a broadly satirical look at the world of big business, tracing the rise of a lowly window-washer as he works his way up the corporate ladder. "It's great fun, and the students are having a blast with it," Drago said. "It's totally irreverent. I think that's one of the things the students are really having fun with. "The play was written at a time when women weren't treated very nicely in the workplace; one of the songs, in fact, is called, 'A Secretary Is Not a Toy.' It's all over the top, and we're taking that and running with it."Admission is $8 for adults, $5 for students under 18. For reservations, call 929-2461.