ahhh okay.
well what i would do is open up a new document in ps, get your Rectangular Marquee Tool (M) & make a selection. that would be your box. then go edit>stroke putting 4 as your width for the stroke. then do a ctrl+j to copy your box to a new layer & a ctrl+d to deselect your selection. after, do a shift+ctrl+n to make a new layer. drag that layer in-between your Background layer & "Layer 1." select your brush tool & add brushes. & there you go!

it would come out looking like this:
is that the effect you were looking to do?

EDIT
i don't think its too much. it's just that some of the brushes, the splatters surrounding the box, are a tab blurry.