Setting up Remote Assitance on two computers

Hello. I'm not exactly sure which board to post this in but since it is
configuration related i thought this one would do. My question is how do I
properly set up two computers to have, and execute Remote Assistance. One
being the assistant computer and one being the host computer. There is an
application I'm trying to share with my cousin which she thinks is very
confusing and I thought suddenly, hey we shuld try Remote Assistance. I know
their are certai ports we have to open and stuff too. The program is so
complicated to her but not to me and I thought I'd show her how to configure
and use it through remote assistance instead of having to create specialized
tutorials for her. If any one could please help, thatd be great thanks.
Thanks in advamced as well.