The following guide will show you the steps to be able to connect to a wireless network using Windows 7.

The first step is to ensure that the wireless adapter you are using is enabled for use.
To check this right click on the icon circled to the right (located bottom right of screen next to the clock), then select Open Network and Sharing Center.
This will open a new window. Click on change adapter settings to display the network connections your computer has installed.

Navigate to the wireless network card that you will be using to connect to the network with and ensure is it enabled. If the network card is disabled it will be greyed out in the example below Local Area Connection and UK are disabled.

To enable your network card right click on the card you wish to enable and click the first option enable.