1) The left side of the page controls the background color and the right side controls font (or text) color.
This Color Display Program shows 216 colors. These are the so-called "safe colors" (meaning colors that ALL browsers will display correctly).
If you want to experiment with over 16 million colors, try this link:

2) Each of the 3 rows consists of the characters:

Rolling the mouse over any of these characters will change the colors.
Row 1 controls the amount of RED,
Row 2 controls GREEN and
Row 3 controls BLUE.

3) With EVERY color change, the 2 output boxes display the six digit "hex value" of that color.
For example, the value for blue is "00 00 FF".

4) This program is quite handy for experimenting. When you create a color you like, write the numbers down and use it on your webpage(s).

But enough talk - you'll learn quickly just by doing.
Have fun finding new colors and color combinations.