Exporting as mp3

I want to export as an mp3. I searched it up and they do it as save as and then the dropdown has an option. When I try to do this, I only get .mscz and .mscx. Help? Thanks a bunch!!!

!PLEASE READ BELOW!

Edit: I am SOOOOOO sorry if I wasted your time. I figured it out. This is how you do it.
1. Click File.
2. Click Export.
3. Select *.mp3 as the file type.
4. Success! (I hope!)