soo I haven't posted a tutorial in quite a while so here I used Infinite Paint (an art program for mobile) and the Wet Paper brush in the Watercolour section. By the way, Infinite Paint is technically free but you only get three layers on the free version, and I'm pretty sure the fill bucket tool is locked. The paid version only costs about 1-2$ CAD though, so I think it's worth it.
Art and tutorial by me. Don't steal my art. You can use this tutorial (obviously)! Remix with the results, I'd love to see them. If you make something with this tutorial, you don't really need to credit me for the tutorial (after all it is you who made the art) but I'd prefer if you acknowledged that you made it based on this tutorial. I used my tablet for this. It took around half an hour to draw.