-open up an image.(for example:legos)then click on the marquee tool.
-then marquee the shape you want.
-then click on edit.
-then click on define brush set.
-then save it.
-then go to your brushes.and it should be in there.then click on it.
-then click on the top right hand corner.there should be 3 buttons.one workspace.then the one to the left of that.then the far left hand corner one.click on that.
-then the brush preset should pop up.
-then mess around with them.
-then on the far bottom right hand side corner.there should be a button that looks like the create new layer button.click on that to save it.
-then it should be in your brushes.--
ones i made: