its kinda hard but ill tell u. but u can only do it on a computer. so u go into normal drawing thing not beta and draw two lines of the colors u want to switch, side by side. Then u go to settings and press the red down arrow. That will download it to ur computer. Then u go into beta editor and u go to settings, press the green up arrow, and select the file. then it will insert it into the animation. then u make it really big, and move it around as u like.