1. This button in the left toolbar allows you to switch between foreground and background colour. The red square in this example shows that red is the foreground colour and white is the background. Click the arrow to switch between these 2. Click the small black and white overlapping squares to revert to default black foreground and white background.
2. Use the Swatches menu to select a colour. This will appear in the toolbar on the left as the foreground colour, to be used by whichever tool is selected.
3. Or you can create colours using the Color sliders. The warning ! sign lets you know if the colour created is within the web-colours range.
EDIT: 3 replies in the time it took me to copy/paste my screenshot and type my reply
