the color of the code does not match that of the web, it is a little lighter

[MichaJo]

lopsidedhow can you set the rgb codes to pick a color?

In GIMP there is a tool "color picker". It's a pipette to get colors of a pixel or an area and to set foreground or background colors accordingly.

A way to set the foreground or background color by entering the RGB - values is the "foreground & background color"    
You will get this
   
There you can set the values for R and G and B. (0..100 means percent, 0..255 means absolute values)