I have my 1/4 inch to 1/8 inch jack plugged into a cable plugged into my Mac's audio in port. I turned the input volume up and my computer detects my guitar. Now, my guitar isnt detected in Garageband so how do I do that?
Go to System Preferences/Sound/Input and make sure that it is set to line-in. Then in garage band make a Real Instrument Track and set the Monitor to On. You should be able to hear it now and can change the settings on virtual amp.
I get some high pitched hiss but it's possible to record
Go to the sound option and switch it from mic to line in, it will def. fix it.