In hte bottom right hand corner of your screen, to the left of the clock, speaker and battery icons is a Ʌ. Click on that and you should see the status of your wireless connection.
An icon of semi circles sweeping left to right without a large dot on the top left means you're connected. Check that your network is in that list. It should be named for the folks you pay for a service. If it has that dot, you aren't connected.
The security key is usually printed on the router. If it isn't there, post back for further instructions to find a way in.