Hi again.

I own and am learning electic/accoustic guitar and someone has given me an electric with small headphone amp so I can practice when the kids are asleep. It needs new strings putting on which I was also given but... I know how to wind the tuning pegs but at the other end each string passes over individual metal part which can be adjusted forward and back to make the string longer or shorter. Sorry I dont know the name of this part. Can anyone advise how these should be adjusted when stringing the guitar please?