Just start it as usual by clicking on its icon or from the Shell. For latter AROS users must set to stack to at least 256,000.
HollyPaint needs the MUIRoyale plug-in which can be downloaded from:
HollyPaint opens at start a canvas window and a toolbar window. Most tools work by clicking with the left mouse button in the canvas window, dragging the mouse and releasing it at the end point. Exceptions are documented in the [Toolbar] section. With the [Settings] window you can influence most drawing actions.
The canvas window has a status bar where you can see:
Brushes are images which can be used for drawing. Brushes can be created by:
These drawing tools support brushes:
Filters let you apply effects to brushes. To use them you need to: