>>124057615Downloading a free art program like gimp is a good place to start. Once you do that and learn how to use the program, the best way to learn is simply by doing.
Learn how to use the pen tool, figure out how to match color and shading effectively. The simplest thing you can do is simply make things bigger, it requires little to no messing with the background to get it right. Once you have a grasp on that, you can move onto more ambitious things like outfit changed.
The simplest way to learn is genuinely by picking up your tools and playing around with them. It may take some time but you'll learn what works for you and what doesn't.
