Below you will see 2 green arrows. The arrow on the left is pointing to the fill control and the arrow on the right is pointing to the stroke or border control.
These controls appear when you click on images and shapes.
Fill - Fill is the color within a shape or image. You can change the fill by clicking on any of the colors that appear once the control is selected. You can also remove the fill to only display the stroke/border. Just click on the circle with the slash through it.
Stroke/Border - Stroke is the color that borders a shape or image. You can change the size and color of the stroke/border by dragging the circle highlighted by the green arrow or by clicking on the bar line and quickly selecting the size you want. To change the color simply click on one of the colors from your theme at the bottom including black and white.
Text Color - Text color is just that the color of your text. Highlight the text you'd like the change the color of and then click on the colored circle below to open all of the colors from you them including black and white.