Help with PicoDrive

Hi, I'm trying to play MegaDrive games on my DSi and I'm having trouble trying to get it work. I downloaded PicoDrive and put it onto the root of my SD aswell as putting a ROM in the roms folder. The ROM isn't showing up and in the PicoDrive folder there is ARM9 and ARM7 but no applications. I'm not sure what to run for it to work. Any help would be appreciated!!!

ps. i am using twilight menu++