Can't get Fusion364 to open sega mega drive

Running windows 7 pro 64bit
Processor: Intel core i7-4790k 4.0ghz
RAM 16gb

Sorry guys kind of a noob when it comes to this but looking for a little help. When i download Sega games individually i have no issue using fusion to open them. I downloaded the mega drive but when i try to find the file it will not pick it up at all. When i browse it says its not supported file. I tried the Gen emulator to see if i could get it working and still had same issue. Im sure im just missing something simple but can't seem to figure it out. When i download individually it says its a "md file" on the mega drive its a "gen file". Im guessing this is my root issue. Any ideas?

Just change the extension from .gen to .md

Fusion will have a drop box where the extensions are when attempting to load a file, you can see what it supports there.

.gen and .md are the same file type its just the extension name that is different.

If you want the best Genesis/Mega Drive/GG/Master System/Sega CD emulator I highly suggest you use Retroarch, they ported the most accurate emu for those system to it, Genesis Plus GX.

It greatly triumphs over fusion as it is open source and is actually kept up to date and it runs beautifully.

Thank you