hey guys i look in the playstation store and i can't find heartfire for skyrim

You might be able to find an answer over in the PS3 forums.

And it isn't available for PS3 yet.

This. There is open discussion in the "dawnguard section" of the forum.
http://www.gamesas.com/topic/1419100-ps3-release-for-dawnguard-thread-30/