Check the tutorials section or use the search button, you should find plenty of things on adding borders. It's quite a simple process unless you plan on creating an intricate border, but plain borders are very quick and easy. Just search around the site.
i cant get the border right i dont have the steady hand to make the straight lines is their another way
Quick tutorial for simple border: 1. Create a new layer (make it the top layer) 2. Press Ctrl + A to select all 3. Go to Edit > Stroke 4. Make the colour black or whatever you want, make it 1 px in size, and then hit OK You're done