Be careful when gripping the pen – otherwise you might right click accidentially!) To change the type of brush that you’re working with simply right click anywhere on the canvas (If you’re using a Wacom tablet, the lower half of the rocker switch serves as right click.
For your purposes the brush tool will be the only thing you need to add pigment to your canvas. This single tool can take nearly any form – ranging from pens and pencils all the way to watercolor and rubber stamps. So where are the buttons for airbrushes? Spray paint? Markers? The answer is found in a single tool: the Brush tool. This seems like a reasonable distinction – after all, traditional painters have brushes, pencils, airbrushes, pens, and more. You might notice that the tool palette contains both a Pencil and a Brush tool.