If you look into your case you can see what fans you have, you can have up to 3, from what I read though you'll have two, one on the side and one in the back. If that's the case then you can get one more for the front. Before you install it though, check the direction of your present fans, if they both blow out then make this one blow in. If one already blows in then make this one blow out.
Also, are your hard drives right on top of each other or is there space between them? If they are on top of each other than try moving them to bays further apart to give more room for airflow.