Magma

save states

I used one of the .srm files and this showed up, what does it mean?

I'm fairly new to roms and I've never edited any, so I need help using PKHex. I have a file that I wish to edit, and PKHex opens and works fine, however I do not have a file that works with PKHex. I use Retroarch, so I don't have .sav files, instead my files are .gba and .nds. Does anyone know if there's a way to use those files instead of .sav files, or if there are any file converters that allow me to convert the files to .sav, edit the files, and then convert back so I can play them again?