How to Editbox changing another variable

[Seeds]

Editing this post for a clearer questions.
For testings sake I made a simple script:

Gui, Add, Edit, r9 vMyEdit w135,
gui, show

Enter::
msgbox, %MyEdit%

When I enter text into the box it should change the variable of "MyEdit" right? But when I enter text into the box and press enter the message box shows up blank, what am I doing wrong here?