1. Register on the forum.
2. Sign up for an account here: http://www.supremacy.game-host.org/
3. Download the game client and all patches: Here
Step 3 will take a while. Post on the forum or something.
4. Make sure you're patched to our current build:
3.0.2.8926
5. Edit your realmlist.wtf file to say:
set realmlist supremacy.game-host.org
set patchlist supremacy.game-host.org
6. Play and enjoy! If you had any problems with this guide, please refer to our other connection guide and FAQ.