If you’re reading this post then you probably want to use an MP3 file as the sound played by your Android phone when it wakes you up in the morning.
To do that you just need to create a folder named alarms (lowercase) and put the MP3 file under it.

IMPORTANT NOTE: you might need to reboot your phone in order to see the new alarm tone

P.S.: I’ve got a Samsung Galaxy i7500 and that worked for me. However, it should work for every Android phone.