Click on the network icon in the taskbar (at the bottom right of your screen, just next to the clock).

1. In the list of available WiFi networks, you should be able to find one or two which match your routers SSID (network name).
2. Once you've found the correct network, click on it and make sure you check "Connect automatically" or "Anslut automatiskt".
3. Click "Connect" or "Anslut".
4. The WiFi key (or nätverkssäkerhetsnyckel) can be found next to the SSID, marked "WPA" or "Wireless Key".
5. Click "Next".
6. Done!