If you have Windows XP and your computer has a downloads folder (look in My Documents);
1) Download the colorset from whatever source you're downloading it from. After its finished downloading, the file should appear in the Downloads folder as a .zip. Do not unzip the folder. Right click on it and cut it from the folder. When you have successfully done so, it should be slightly transparent.
2) Go to your Documents folder, and click the folder up button (a folder with an up arrow). It should list a bunch of your computer drives; click on the C: drive, go to Program Files, Blockland, and look for the addons folder. Open it up and paste it anywhere in the folder but be sure you're not pasting it into something else.
3) Next time you open Blockland (close and reopen if you had it open while placing the addon) go to Start a Game and click on Color Manager and click Truenos. Voila.
But of course RTB is easier lol.