Hello.
There is a chance that the version of Excel you are using might not accept HEX color codes and only RGB.
If this is the case, please open this link. This is for a HEX to RGB converter. If you want to use the exact colors I use in the next tutorial but you can't insert HEX codes, you can use this converter to get the correct RGB codes.
Alternatively, you could use any RGB color scheme you want.
Warrick ;)