Notice that I have added text that say's "Stroke & Color Fill"

When dealing with text your stroke color will set up what color your outline will be and the fill will be the inside color.

You can select you color 2 different ways here. You could simply left click on the color you want in the upper most color palette to choose your Stroke color & Right click there to choose your Fill color. Or you may click in the center of the actual Stroke color box to choose a color for it, and click in center of the Fill color box to choose it's color.

When you choose to select from the actual color boxes it will pop up a new window. (Information for that below)

This is that same palette but using the "Swatches" View. To view it simply click on the tab marked swatches. You can select color from this one the same was as described above.

This really comes in handy when you are reproducing and need to use the exact same colors as you used previously.

Gradients are a unique way to fill and add an extra touch to your area.

You can also change the way the gradient is used by changing the angle, repeat, style etc...

Play around with these a bit to see what fun you can have.

Whatever you have opened in your work area will show up in this palette, and you can use it to fill your areas with.

I use this palette more than any of them.

This palette can be used in conjunction with your chosen colors. 

If you had a white foreground (Stroke) you could choose a blue background color (Fill) then come here and select a texture. When you go to flood fill now it will take on the texture you have chosen.

I use this more for my backgrounds that anything else.