Connect to your router by lan cable.
Open your internet browser.
Type in the following:
http://192.168.1.1
Hit enter. At the login screen, enter the user name and password. By factory default it's both admin in lower case letters.
Configure the router completely, also the wireless part.
Save the settings.
Then configure your wireless connection at the workstation or notebook with the appropriate settings, network name, encryption type and key.
Disconnect the lan cable and connect wirelessly to your wireless network.