Go to your action window and look for the Macro menu. From there you should be able to create one. You can assign a unique icon as well.

You need to know basic chat command to create macro, use this listing for easy reference http://aquelia.wordpress.com/2013/07...ick-reference/

Few tips:
- Look for dummy monster to test ur macros
- Always put /echo [message] at the end of your macro so you know if something went wrong in the middle.