In the Editor, you have access to all normal paint tools. Nothing special has been introduced (yet).
To choose new colours, either select them in the Colours palette window, which can be shown by pressing command-2 or by choosing Windows->Colours from the editor menu, or you can click on the colour sample in the Tools palette, which will bring up the standard apple colour picker. The difference between those two options is that the Apple picker allows you to choose between thousands or millions of colours, whereas in the Colour palette, you can only choose between the 256 colours that can be used in Icons, hence assuring only convertable colours being used.
Note : The editor works in 16 bit maximally (Thousands of colours) to reduce RAM requirements.
