Here's some tips on some of da buttons:
Dodge: Makes lighter
Burn: Makes darker
Pen: A bit more transpearent than pencil
Spray: Light colour
Pencil: Use this to draw

Squiggly line: Free draw
Straight line: Use this to draw straight lines

Squiggly line with straight lines at the ends: Draw curves with this
Ummmmm........ think that's most of them
