More than likely, you have repeated steps in your digital creations that would be better served by using Actions. Actions are quite easy to setup and can make your life with Photoshop much more efficient.
For the purpose of this tutorial, I will create an action for the borders that I have used on some of the photographs I have taken. I prefer a simple white border. If you plan to add many of these borders, it would become tedious to do so, over and over, thus the need for actions.
Let's use the image I took of the spiderweb. For the purpose of this tutorial, I have cropped and sized the image to 400x250.
Original:

Result:

The first step is to create yourself a folder in the Actions Palette, as I have:

Next, under the folder, select Create New Action. It is important to point out that whatever you do from here on out, will be "recorded" with Photoshop. If you miss a step, or add in an extra step, without correcting that in your action, it will be repeated each time you play the action. Name your new action (I named mine "My Frame") and the action is set to record automatically.
Here are the steps that I followed:
Now, in your Actions Palette, click the stop button to stop recording your new action. Now you should have an image similar to the result image listed at the beginning of the tutorial. To test your action, delete the newest layer from your layers palette. Go to the actions palette, select your frame action, and click play.
If you repeat tasks, I would encourage you to use actions to save yourself some time and headache. Photoshop is equipped with many tools to assist the designer and this is one of the better ones for saving time.