Ok its pretty simple to put security on the router.
1. Open up a web browser and clear the address bar out.
2. Type in 192.168.11.1
3. Username is root there is no password hit enter.
4. Go to advanced
5. Go to wireless config.
6. Choose security
Now you have a few options you can do WEP or TKIP.
WEP you can choose 5 or 13 characters now if you choose 5 it can only be 5 if you choose 13 it can only be 13. If you choose TKIP it has to be 8 or more Characters. When I help a customer set these up I usually have them choose WEP64 which is 5 characters.