Learn to create a dotted line brush, turn you shape to a dotted line, create a cool dotted line border in this tutorial just like an image above.

First, you have to create dotted line brush.
- Create a new document 640*480 pixel.
- Select Brush Tool, then select brush tab at the top right corner.
- Select Brush Tip Shape and select 1px brush(or whatever you want) .
- Edit spacing, in this tutorial 450%, then click on create new brush icon.
- Name your new brush "Dotted Line".
- Click back on Brush Presets tab, at the bottom of the list you'll see you new brush.

Last step you've created a new dotted brush, now it's time to create some shape.
- Create a new layer.
- Select Rounded Rectagle tool or other shape tool, then draw a shape.
- Select Pen tool, right click and select "Stoke Path" a popup window will appear, select brush and click ok.
- Right click again and select "Delete Path", all done.

- This is what I've created using this technic.