Go to Walmart and get a new chain for $6 a brake/gear cable pack for $5 and see what you can do. Get help from a friend and look at a few web sites for help. If you had a few pics it would help. Here are a few sites to help out.
http://sheldonbrown.com/home.html
http://bicycletutor.com/
http://www.parktool.com/repair/
If you can get the bike to shift and brake then get a set of tires.
http://sheldonbrown.com/home.html
http://bicycletutor.com/
http://www.parktool.com/repair/
If you can get the bike to shift and brake then get a set of tires.