I'm not sure if there is a tutorial on how to do that, but there is an easy way to cusomize your own if you would like to use a blank.
Click on the pic you want to use. When the pic opens linger over it and you will see a bar that says file, edit, resize, rotate, etc... Click on the edit link and it will take you to an edit screen. There you can add an effect, border, text or whatever else they have and then save it.
To add text: Click on text and then choose your style, color, size etc... Type your text where it says "type your text here" and then move the text to where you want it. Click apply and the text will be where you want it.
Hope it helps a bit.