How to get to siege mode on star wars Jedi knight jedi Academy? And if not passable were?

I saw a clip on youtube on the siege mode in star wars jedi knight: jedi Academy. I thought that it was so cool that I bought the game but now I don't know how to get to the siege mode.I know It has that feature because there is this one section for rules in the game, and it said that siege mode was on the game AND told you the rules to the siege mode. If it helps, I have the xbox version.How to get to siege mode on star wars Jedi knight jedi Academy? And if not passable were?siege mode is an xbox live multiplayer game