Using your team budget effectively, and how does it work?

Could someone post, or give a link to a good site, which explains how everything works with the budget of a team? Everything from how you can use your money when signing players, trading players, signing them up the mid-level exception etc? I'm not too sure on all of these points so signing players for me is more or less just to see if it works.

I think there's more of us out there who don't use their team budget wisely. How to we know exactly what we can afford and how to plan our budgets for the future?

http://members.cox.net/lmcoon/salarycap.htm

For the year one in Association:
http://games.espn.go.com/nba/tradeMachine
http://www.realgm.com/src_tradechecker/1/

Or just follow what this team has been doing for years:
http://www.nba.com/spurs/