VS 2010 How to create transparent but clickable form?

Hello,
I am trying to create transparent from, with controls inside it.
What I did is:
I created transparent form, used transparency key, selected bg image with black border.
I added button in the center.
I want to make the bg of the form clickable.
here is the image for example:

there is a black border around the form, when I click inside the form its not selecting the form.

How can I make it transparent but when user click inside the form he will be able to move it etc.?

Thanks!