In this very full hour, we covered the different ways to choose and apply color to a picture in Photoshop. First, you learned the difference between the foreground color (the color that's on your brush or pencil) and the background color (the color of the canvas under the painting).
The Color Picker, Color palette, and Swatches palettes all contain colors with which you can paint. The Color palette and Swatches palette are easier to use than the Color Picker because you can leave either one of them open as you work. You learned to use the Eyedropper tool with the Brush to choose colors from the palette or from the picture itself.
Finally, we covered blending modes, the way that two layers of paint or image interact with each other.