How to let users edit the info window in

I follow this tutorial- http://www.drupaltherapy.com/gmap
in order to use gmap and location module.
It's really useful and finally I can contain gmap in every node by puttinng "location map" into "blocks-content" without using gmap macro to paste the code in body field.

However; I couldn't find how to let the node owners to edit their own info window on each marker because there is no filed for users to type information.

I believe it should be in somewhere? Maybe it's just a stupid question because I didn't open some function?

however; I really test everything I could and I also know if you want to show something on the edit info window-
just insert a colon before the lon/lat values for a marker, such as "-117.3233413696289,34.193203619503:LZ - Andy Jackson Airpark"

But users would not know this, and it's not that user-friendly. So can somebody help me how to figure this out?
p.s the attachment shows that the info window is blank and doesn't do anything even I've already chosen the marker action as "open info window" in gmap module setting.

Best

Annie