How do i embed into my home made WP theme?

Hello all,

Some time ago i created a Wordpress theme for my blog.
Yesterday i started using the WPG2 plugin (version 3.0.7)

I configured it so Gallery2 Pages look like a Wordpress Page.
but when i go to the /wpg2 page it looks like it's using the default wordpress theme.

i think my theme lacks something?

my WP theme is build up like this:
style.css
index.php
functions.php
comments.php

is there something special i should do with my theme to enable gallery embedding?

Thanks for helping me out

Piet