Macbook Air -- connecting guitar

so I am getting two stories on this. that it can work or it can't.

My Macbok only has a headphone input.

When I put the three banded plug from the mini plug into the MacBook air, it doesn't allow me to change input

but when i use a four banded Apple headphone, it allows me to use the headphone as an audio input.

So can I use a three band to four band converter and make this work?