Transferring Music files from a PC to an ipad

I currently have music in my PC and cannot seem to transfer it into my ipad. This is downloaded music from old cds etc and not necessarily purchased through apple store. They are currently at home in a I itunes library folder under music but I just don't have the knowhow to get the music across. My ipad is 128 GB and should cope with the increase library as it also has downloaded music collected over the past two years