excel

I basically need to help someone with an assignment. Don't ask why, I've been asking "why me" all day long. The problem is I don't know much about Excel. I'd be happy to learn but the time-limit is rather pressing. The assignment is here (.doc file) and what the student has done so far is here...

i'm trying to make a simple spreadsheet where in one cell i can type in the time an employee starts, in another cell the time they finish and have the hours worked pop up in a third cell (automatically deducting one half hour for lunch break) example. cell 1a, i type in 6:50...