HALO 2

My current goal is....to finish all of the video games that I own. One of the X-box games I am (still) stuck in is HALO 2, I'm so lost I don't even know where I am in this game. If anyone can give me some tips I would really, really appreciate it. I borrowed (OK, more like "adopted") this game from my Dad, who never really gave it a chance.

HALO 2, the current bane of my existence.

"Halo 2 takes place in the same science fiction universe as Halo. According to the story, humans have colonized numerous worlds due to the development of faster-than-light travel. Twenty-seven years before the beginning of Halo 2, the outer colony world of Harvest was destroyed by a collection of alien races, called the Covenant. Since then, the humans and the Covenant have been locked in a bloody war, with the UNSC forces continually losing major engagements. The Cole Protocol was created in the hope of preventing the Covenant from discovering human population centers, particularly Earth itself. However, shortly before the events of Halo 2, the Master Chief heads to Earth after destroying a Covenant fleet to ward off an impending Covenant attack on humanity's home planet."

Again, if anyone can help me with this game (I mean win this game,) that would be awesome.