How do I find out what my security key is?

First connect your router to computer with ethernet cable.
Then access it with following link.
http://192.168.1.1
or
http://192.168.0.1
type user as "admin" and password as "admin" or blank or "password"
then you can see configuration page of router settings.
Go to wi fi or wireless menu then find WEP or WAP security code key it is your password to connect wi fi network.If it is in * or # format then add new code so you can connect it with new code.
then save settings and restart router.
Let me know if you need more assistance.
Thanks.