updating

Im haveing trouble figureing out of to update my anano, i ve download the fiels but i don kno how to transfer them to my nano can any1 explain

further more, my ipod fromm time to time skips ( ZAGZGAZAGZAG noise) n wil stop when i press next, its happening to prefect fine workin songs that work very recently b4

any explaintion/souluton

thank u for ur time 😀