How to play electric guitar through garageband

Hi,

Macbook Pro mid 2009 running OSX 10.10

GarageBand 10.0.3

I have seen on the internet that it is possible to connect my electric guitar to my Macbook Pro and then use the Amps and effects in GarageBand to produce different sounds and effects from my guitar.

I have tried with a couple of different cables (standard 1/4" with an adapter as well as a Rocksmith USB cable), but GarageBand is not producing any sound.

I have repeatedly checked my input and output Sound settings, the cables, making sure I have the cables plugged in properly, but still nothing.

I've been working on this for a week and I'm stumped!

Help appreciated.

Regards,

Jim P.