From the manual, do the follow (note all models have an actual wireless switch):
Windows Wireless Network Connection
Connecting to a network
1. Switch ON the Wireless function if necessary for your model (see switches in Section 3).
2. Press [FN+F2] repeatedly until wireless LAN icon and Bluetooth icon are shown. Or double click the Wireless Console icon in Windows notification area and select the wireless LAN icon.
3. Click the wireless network icon with an orange star in the Windows® Notification area.
4. Select the wireless access point you want to connect to from the list and click Connect to build the connection.
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http://dlcdnet.asus.com/pub/ASUS/nb/X75A/E7051_eManual_X75A_Z104.pdf