Solid Border
Making a solid border is easy and quick; and it can make an image look neater or more intac.
1. Open up your image/graphic that you want to put a border around.
I'm going to use this as an example:
2. Next, select the rectangular marquee tool which looks like this: 
and using that tool, click and drag it from any corner of your
image, and drag it towards the opposite corner. (So it should end up around the whole image.)
3. Now, right click anywhere on your canvas/image and select the option
stroke.
A little new window should pop up. Where it says ''Width'' put in the number of how
thick you want your border to be. I chose to have my border 3px thick.
And just match the rest of your settings to mine:
4. Once you're done, select OK, and here's what I ended up with:
