Help Me Build A Gaming PC

I always knew that I wanted to do gaming. Right from the moment when I first started playing Super Mario in my cheap Atari-type console. From there I went on to play games likes Mission I.G.I,G.T.A Vice City, Call of Duty and all of its version till MWIII. But soon my PC became obsolete with its Intel Celeron chip set and integrated graphics. So I had to give up gaming. I'm 18 now, just out of high school and too broke to afford my own Gaming PC. So here I am hoping to get some help.