If you'd like to make more commands & leaderboards, if you know what you're doing; you can edit the skript itself OR
Make another file for the new command, but change the command so it doesn't give an error!
Installation
Go to your 'Plugins' folder in the files of your server.
Go through your plugins until you find 'Skript'.
Enter the Skript folder and click on the 'Skripts' file. You should now see around 10 disabled Skript files. (If you are using the newer version of Skript)
Now drag and drop the 'ChatLeaderBoard.sk' file into the 'Skripts' file.
Go to Minecraft and run the command "/sk reload ChatLeaderBoard.sk"