To connect my window7 to wireless net work

IF you have a wirless router, with wirless enabled, the defaults will normally be on a label on the bottome, but you should access the web interface and change this.

A desktop PC will normally require a seperate card physically installed, along with drivers.

A wireless enabled laptop will have this already, but may be switched by a switch or via the FN+Fnn key.

W7 should then say it has found networks and just click on one to connect, you will then get prompted for security key.

A lot of newer routers also have something called WPS, which is a button you press and for two minutes looks for a pc trying to connect, very similar to pairing bluetooth devices.