Here is a link to the box art for the Sega Genesis:
https://drive.google.com/file/d/1L5myt5tjtxQKB0SyRxL9TM-dNLE6CSKp
Here are some examples in the pack:
To add the box art to the games:
1. Add them to the SD card. I put mine in a SMD folder I created in the Media Folder.
2. Choose the "MEGADRIVE" emulator from the menu and click the 'Select' button.
3. Select "Edit MEGADRIVE" and scroll down to the Box Art option and click 'A'
4. Navigate to the SMD folder you put the Box Art in and click the 'Start' button to exit.
The cover art image files have to match the rom name exactly or they won't show up.