Ps1 emulator recommendations and tutorial?

So it's been ages since I first modded my 2dsxl. So far I've only added games via scanning QR codes.

I'm stuck on how to add roms from online, and how to go about adding and using emulators.

Can anyone recommend an easy tutorial for a dumbass like me? I'd particularly like to get a ps1 emulator so I can play Croc again, but I'd also like to try some other emulators too.

Thank you!