The easiest way to do text is to just type what you want it to say in something like wordpad, then copy/paste the text into Paint.net as a separate image file. Then reverse the color so the text becomes white and the background becomes black. Then use your magic wand tool and select the black background, hold shift down and click your wand into the black areas of text like the center part of something like the letter O. Then delete the black so all you are left with is the white text and a clear background. Increase the canvas size by 200% and center your text into the area. The drop shadow the text or outline the text with black. Select the text and copy/paste it back into the cover where you want it. Pretty simple once you get the hang of it.