Show Modal From User Control

Hi Forum, 
I have a simple modal on my page, that I hard started using in a number of places.
I want to convert it to a user control, I am currently called in from the code using  ModalPopupExtender1.Show()
If I want to now do this using a user control, how do I do this, do I need to create an event in the user control an expose it back to the page code behind ?
I dont know where to start
Graham Mattingley
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