is this possible?

[LordLickly]

could i make a marine army with a titan or two in it??

new to this.

[WackyOne]

Sure!

Marines (and almost everyone else) can spend up to 1/3 of their points in Titans and Aircraft.
A Warhound is just shy of 300 points, so you could use one from 1.000 points on - mind, it will be a significant part of your list at low points.

Not to be rude, but if you need a copy of the rules (the army lists are included), there are links in this thread: http://www.librarium-online.com/forums/epic/88775-epic-questions-epic-game.html