Any time that you use a tool that has line or fill, you'll have the option to set you line and fill colors using the color pickers at the bottom of the main Toolbar; you can also click the Black and White button to set the colors to default black and white, the No Color button to set no color fot the line or fill (depending on which is selectable, as they are clickable to switch between options for each) or the Switch button to switch up your colors for lines and fills. If you change the line or fill colors in the toolbar while a shape is selected, the shape's colors will change to reflect it automatically.
More options can be found in the Properties bar whenever you have a tool selected that uses lines, fills, or both. The color pickers are available here, as well, but there are also more advanced options for lines/strokes.
