If you want to directly code colors, remember that it is in the order of RGB (Red Green and Blue)
And the brightness of each color is in a range of 0-255 or 0- #FF in hex.
So for Orange, you can enter:
#f90; into your CSS declaration where we have bright red mixed with medium green and no blue.
Or for yellow, go with: #ff0;
To get more granular (precise), you can expand out the bit range such as with:
#f8f8f8; for off-white
In hex there are 16 values as per: 0123456789abcdef
These are the brightness levels that you can use.