Hi Richard. I'm completely unqualified and a total idiot, but I can help you just the same.
WPA and WEP are actually not addresses - they're what's known as encryption protocols. WiFi transmits data through radio waves, so anyone with the right kind of equipment can 'listen in' and see everything that's happening on your network. Obviously, that's not good.
The industry has developed encryption protocols to encrypt all the data being transmitted over WiFi, so even if someone is able to see what's happening on your network, they won't be able to do anything with it because it's encrypted.
WPA and WEP are older, and they have already been 'broken,' meaning that the encryption can be decoded. The newest encryption protocol is WPA2, and that's the one you should be using.
In a network, an address - which is formally known as an IP address - is a set of numbers that is assigned to a device on the network. It's just like the address of your home. Just like your address makes it possible for people to find you, a network device's IP address makes it possible for a router to find the device.
If all this sounds complicated, well, it is. That's why routers are setup to automatically assign IP addresses to devices on the network, like your printer.
Your router should be using the WPA2 encryption protocol. Your printer's IP address should be automatically assigned by your router. There are a few ways to find out what your printer's IP address is. One way is to open your router's configuration utility. The address will among the first screens you'll see.
If you need help with any of this, just ask. Once you understand it, you'll say "Oh, is that all it is ..."