[Q] How to install CyanogenMod on Galaxy S3 topic

Hi
I wish to install CyanogenMod on my galaxy s3 but since i have never rooted or tweaked my phone i don't know really know where to start or what versions I need to install. I did come across the CyanogenMod installer but am not sure what android version this will install e.g. android lollipop or whether it will be stable etc.

Please help me out and sorry if this has been posted before

thanks