Turn a custom module in to a related list

I have created a custom module, and I'd like to see it as a related list on my Accounts page. When I try and add a related list to the Accounts page (By choosing "Select Unrelated Lists", it tells me that "You have already added all your related lists for this module."

So I'm guessing my custom module isn't actually a related list... yet.

Any assistance on how I can link my custom module to my account records would be greatly appreciated.