As we slowly pry the information from you, will we give up before we get it all ? I still don't really know what you're doing or why.

What's wrong with your old wheel ? Got a picture of it ? You have a new wheel ? So you need a cassette to go on it ? If your shifters are 7 speed, then you need a 7 speed compatible wheel (not 8-9-10). Why can't the bike shop order the parts, or at least tell you specifically what you need, since they have seen it in person ?

Here's how you could have made your first post:

Hi, I have a Schwinn mountain bike. It has 7 speeds and I'm replacing the wheel because _________. Below is a picture of the bike, and here's a closeup of the old wheel & cogs. What kind of cogs do I need to put on the new wheel ? Or can I move them over ?

Try to give as much info as possible in the first place next time.