The Methods
(apart from using the paint bucket to fill)

1.Lets start by creating a new window 'Command - N'
of say 10 x 10cms @ 200ppi.

The colour swatch on your tools palette holds
a foreground and background colour. You can
switch between these at any time by hitting 'X' .
See below;

if you hit the 'D' key you get the default Black and
White colours (above right).

2. Lets fill the new window with the Foreground
colour, as a keyboard shortcut;
Foreground colour = 'Shift-Option-Delete' (Shift-Alt-backspace)
Background colour = 'Command-delete' (Control-backspace)

3. Lets fill the new window with the
Foreground colour, as a menu task;
Go: 'Edit - Fill'. A dialogue window will
appear asking if you want Foreground
or Backround. Choosing the Background
gives you this.



4. Choose 'Edit - Fill' again but this time choose the
Foreground colour. This gives you...



That's it!