Asterisk external sip gateway

Hello all

im totally new to Asterisk and all its configurations but im trying to set up Asterisk to use an external sip gateway.

So far i have successfully connected to two phones so they can call each other (that was a landmark in its self lol)

but i cant find how to set asterisk to point at the gateway?

the gateway is a Pheenet VG-1440R

help!! lol