WEP and WPA/WPA2 are wireless encryption protocols. They are, in essence, "passwords" for your wireless network, to keep people from piggybacking/stealing your bandwidth.
Go into your PS3's system menus, go to settings, Network Settings, Internet Connection Settings.
Choose Easy mode, then Wireless, then "Scan". It will detect any available wireless networks. Look for the one with your network name (if you've never changed it, it will probably be something generic like "netgear" or "home").
From there, choose the available settings. Unless your router is ANCIENT, it will use WPA/WPA2. As for the password, if you never changed it, it will probably be either blank or "admin" (no quotes). If you have, enter your password and you're good to go.