I'm not exactly sure what this is called, but I learned how to do it from my art teacher, who got the idea off the internet. It's just a really fun thing to do, and it turns out different each time you do it. Once you learn the basics you can use different ideas to create different things with it.
Step One: Draw a swiggly line across your paper. Be as creative with that line as you want, it doesn't even have to go from side to side. It can go from top to bottom, side to top, whatever! Put dots along the line at different distances.
Step Two: Using the dots as your guide, draw loops coming out from one, going to the next one. From one dot to the one beside it....and keep doing that on top of the one you did, layering, and always coming back to the dot (or at least making it look like you did).
Step Three: Continue to do that for all the dots, below and above the line. This is hard to explain but hopefully you'll understand by looking at the picture. Do that until it's all filled up!
Step Four: Add color!!! One of the best parts! You can do this with basically whatever: Colored pencil, sharpie, etc.
Step five: Continue until you do the whole thing with color!
Ta Da! You're finished! Let me know if you have questions about it. Hopefully the pictures will tell you what you don't understand, because it's really hard to write explaining it!
Note: Here is an example of something you can do with the same technique: Flowers! Use a center dot and draw petals around it, adding layers like you did with the original.
P.S. Then you can create new ideas with this technique! I'd love to see a picture of anything new you come up with!