This is the options screen, you get to it by clicking on the Options tab at the top of the screen. Look at the middle column: make sure your connection is set to "Internet," that "Register in Lobby Server" is checked, and that "Maximum Players" is at whatever value you want.
All you have to do is change the Game Name to StarDome and the Password to SoldatBoys.
Then, click on the Start Game Tab: select "Capture the Flag" and then choose the maps you want to play by clicking on the arrow under "Maps" and clicking on each map you want to play (you may also click "Loop" to play indefinitely -- the server will never close).
Finally, choose the maximum number of caps or points (the map will end whenever one of those numbers is reached).
All of that is if you want to play. If you just want to host the game for others, you'll have to do that through the dedicated server, which is a whole other deal.