I recently bought some flush fin retrofit windows. They don't have a nailing flange, just the decorative fin. I'm building a shed, and want to put vinyl siding on the shed.

From what I understand, these windows are meant to be installed flush with a flat outer wall surface. Have I made a mistake by buying these windows?

Or how can I install these windows over or under the vinyl siding and somehow make them work with trim?

I just want to try and make them look nice and not leak.

Thanks in advance

(Ps, yes window is upside down in the photo, it is right side up now)