In your Learning Center, click the Home icon, if necessary. Once you are back at that home page select the Text and Graphics option. The Learning Center display will change to show you the available functions for this option. Select Add Borders.
The Add Borders dialog box will display. Select the color you want your border to be by clicking the color swatch then selecting the color from the Color Picker when it displays. Make sure that symmetrical box is checked so that the borders will be even all around your image. Set a number for the amount of pixels wide you would like the border to be. I set mine to 70.