excel help??

Hello,
I am trying to create an excel spreadsheet that works like a time sheet. Colums for time in, lunch, total hours worked, and comp time. Seems simple enough. I am a novice on excel, and have the spreadsheet created, however, I am wondering if anyone knows what formula i would use to have the sheet do the computing for me. for example, in at 7AM out at 4PM 1 hour lunch.....I don't know how to make to calculation work. The queries don't seem to like the time format. Any suggestions would be greatly appreciated!