To see the whole world in the map:
Use your mouse "scroll wheel" to make the map view zoom in or out.
When I click JOIN, a little box comes up that says "Hi! Please add yourself! Where are you? Move this pin."
To move the pin, click on the words "Move this pin" and a box will come up asking for your address, city, state, zip or country. Once you enter some info in that box it will set your location.
You should see me right now; I brought my laptop over to my family's computer so I could sign in on Frappr as a new member and test this!
I keep on getting the mice confused for the 2 computers I am sitting at. Good thing the kids are all asleep or they would be making fun of me for sure.