Simple Line Border.

In this tutorial, I am going to show you how to do a frame like this:
You can use GIMP to do it, too. Go here for that tutorial.

1. Open PF and open your image. I'm going to use this.

2. Go here:

Make a selection. I'm going to make it like this: 

3. Go to Filters-Frame-Simple Frame. Select a color, adjust the opacity and the width (it looks good if it's 1 or 2) and you're done!

You can make even 2 borders using the same method, making one with the width 1 and the other with the width 2.