Need help with downloading roms

Hi everyone, I’m new to Legion Go. I’ve never had a steam deck or nothing of the sorts but I thought I would give it a try. When buying it I spoke with the Best Buy guy and he told me I can play emulated games on this and that’s what intrigued me into it. So I decided to buy it and give it a go.

I set my legion the way I wanted it and downloaded emudeck on it as well. But I’m having trouble on how to download the roms onto the device.

I looked at many YouTube videos and read a lot of forums but I still don’t quite understand it. So I turned to you guys for help. I appreciate any advice you guys give me. Thanks in advance to all of you.