First of all, I am sorry for spamming your feeds and timelines with my hand-lettering and typography. I think it's actually a good way to express words of encouragement for yourself and for others. And, and, and it's therapeutic. Pretty easy to do, too. So, go grab a pen and try it out.
I'm not going to teach you how to do typography here, because I have a strong sense of individuality, and I think we all have to develop our own styles. Instead, I am going to teach you how to do overlays, and it's easy as 1, 2, 3! (and four)
Step 1: Scan your work. I don't have a scanner, so I just took a photo of my work (lol be resourceful).
Step 2: Open in photoshop. Make necessary adjustments in the contrast and brightness of your work. After that, go to Image, Adjustments, then Invert. The only colors you should be seeing are black and white. No grays.
Step 3: Select the entire image (including the black background), and place it on top of a desired background. Make the necessary size adjustments.
Step 4: In the Layers tab, choose Screen, Color Dodge, or Linear Dodge, depending on the best outcome of the overlay.
Congratulations! You are done!
Here are some of the stuff I made for my org and my Tumblr.
Hope this helps!