How do you make a custom level for marble blast gold

This took a long time for me to write.. so please respect it by Shane Coleman
First push ~ (for windows only)
or push F10 for macs
Then type : testcheats=1;
then push enter then F10 (or ~ on windows)
push F11
then F4 and fiddle around to learn how to work it. Also push F8 to fly around the level to edit and push F7 to drop.
Low Gravity Cheat: push F10 (for macs) or ~ (for windows)
type: defaultmarble.gravity=2;
to unlock all levels click on the bottom right of the blue selection screen while selecting a level. NOTE: this does not unlock custom
Special Mode: Complete all gold times
Custom levels: first download custom levels from garage games (http://www.garagegames.com/marbleblast/levels.php) and click the one that's 12.7 MB and then go to C:/program files/marble blast/marble/data/missions/custom
Then place the custom levels inside the custom folder and then open Marble Blast gold and click the custom tab and have fun!
NOTE: You MUST create a folder called custom in C:/program files/marble blast/marble/data/missions