Step 1: Move all the elements you are going to be using onto a single transparent .png.
Step 2: Move all the elements close to or overlapping one another - you can rotate, resize etc at this point until you have something that pleases you. Here is mine:
Step 3: At this point you will apply a mask to every layer in your composition. The default mask will be white and a little rule you may like to commit to memory is black conceals, white reveals. So working on each mask with a black brush you can "hide" parts of each image that you do not wish to see in your finished stamp.
Here is a photo of my slightly changed composite.
I am sure you cannot see too much difference here. If you want a more distressed look you can of course change the size and type of brush you use and change the opacity as well.
Step 4: You are now ready to make all your layers into a single layer. The best way to do that is highlight the topmost layer and hit shift+control+alt+e which will create a new layer with the merged image. (you also need to turn off your base layer if it is not transparent).
Step 5: Working on the merged image layer place your cursor in the layer in your layers palette and do control+left click and that should give you marching ants around your merged image.
Step 6: To make the brush - with the marching ants visible go to edit>define brush preset and a new dialog box appears. Give the new brush a name and hit OK or save and you are done.
Below is a layout I made with the brush I created.
Your next stop will be: