Adobe Photoshop Painting Questions?

okay I love to use Photoshop and I know quite a bit about it, but I want to learn more. I was on youtube and I saw some speed art paintings and i thought that it was amazing how they don't have to look for a picture to manipulate they can just create it. The problem is i don't know anything on the painting part of Photoshop. Is their a video or something i can read that teaches me the basics on Painting in Photoshop and then gets more into detail once I learn the basics? I think that if I learn how to do this it can help me a lot with my career in the future.