Have you gone and read the links people have already given you?

You don't really need any 'special' software, Just something that can record you playing and singing to your computer. Go to Recording Your Music to see some recommended programs for this purpose.

Yes you will need a microphone to get the sound onto your computer.

Once you have recorded with one of the programs mentioned at Recording Your Music, and saved it, the file will be on your computer.

You can then UPLOAD that song file to your songs. Go to Song Guide for information on that.