Website colors are defined by three numeric values. One for Red, one for Green and one for Blue which is stated as RGB, the primary colors. All colors are a combination of these three primary colors.
Now, each of the three colors can have a value from 0 to 255 decimal (the number system most humans use) or 00 to FF hexidecimal (the number system most programmers use). The hexidecimal or HEX value is more commonly used by website designers. So, let's use the HEX values.
For a quick elementry review, the decimal number system is base 10 and uses 10 digits, 0 thru 9. The hexidecimal system is base 16 and uses 16 digits, 0 thru F (A=10, B=11, C=12, D=13, E-14, F=15). That's where the A,B,C,D,E, and F come from. No, you don't need to dwell on this techie stuff. Just bear in mind that this is the number system that programmers use because... well just because.
Let's continue. It's easy to see that 00 represents none of that color and FF represents 100% of that color. Combine different amounts of R, G, and B to get ANY color. Turn on 100% of R, G, and B and you get white (RRGGBB = FFFFFF). Turn them all off and you get black (RRGGBB = 000000). This is not rocket science.
Now, let's find some colors for your website.