If you recorded with Pro Tools, you can send the whole session folder to email@example.com. If you recorded with anything else, please send the separated tracks (like lead vocal, ad libs, etc). Just make sure that each track lines up at the beginning of the song. Meaning if your verse starts 2 minutes into the song, there should be exactly 2 minutes of silence on that track before we hear your voice.
The files will probably be too big to send directly through email, so you can use a free service like WeTransfer.com to send them over.