I'd suggest a different program to begin with. Small free to use programs like that don't come with much to offer, or a way for people to add-on to it.
There are other programs you can use that are popular on here. GIMP
Click the orange button to download directly. This is basically a free version of Photoshop with most of the accessories. It's a popular program and it's easy to find new brushes and tutorials on how to edit/draw things on it.Paint Tool Sai
Commonly called just Sai. This is a custom version from a popular artist on Deviant Art. This is probably the most popular program used on here. It's basically a stripped down version of photoshop, only having the basics and a few settings. It's popular with people who know how to draw because of things like line smoothness settings, blending, etc.
Both downloads are safe. You can find GIMP brushes to download and use, but Sai is basically a program where you create your own brushes by playing with the settings. If you choose to use GIMP, deviant art users have a ton of brushes you can download.Click for Brushes