STEP 1: Go to the Server Admin tab and click on Server Info.
STEP 2: Scroll down to Extensions (A) and click Edit Extensions (B).
STEP 3: You will see a view similar to the image below.
STEP 4: Click Add and name your extension.
STEP 5:. You will now see the new extension listed in the 'Extension List'. Select the extension you want to edit, and click the Edit button. You will be able to edit the code for your extensions. Once you are done, click Save.
STEP 6: . Now that you have created an extension, select the extension you wish to use and press 'enable'.
The Move Up and Move Down buttons determine the order extensions get called (with the top extension executing first).
Disable will move the extension to the 'Disabled Extensions' and will not be called.
Remove will delete the extension all together.