Mmm, only advice i could give you is trial and error,
You have a "blur" tool in left panel where you can choose your tool. May be it can do the job, other than that , try to go in the render sections (i dont remember the title )
there you should see some blur options, render:pixelate, lens effect, artistic, etc... all the filter are there.
Theres also brush filters, just look around youll find them, my photoshop isnt installed so its diffficult to remember all the item right now.
Hope this help.