I do think i have a router but do i need a public IP?
Router = internet = WAN IP (public IP as you put it)
If you can connect to the internet, and you obviously can, you have a public IP.
I said before, you have read the instructions wrong, or you haven't even bothered to try and get ports sorted out.
'I do think i have a router'
Look on the wall or near your computer for a box with lights on it.
If you don't have a router, go away and get one, then your problems will be over