Where to buy music notes?Watch
There are for example previously mentioned sheet music (it's a store-bought version of a song printed by a publisher), songbooks (they are are compilations of many tunes), lead sheets (they contain lyrics, chords and melody line of songs, they're used usually by professional singers and musicians), fake books (comparing with previous types they contain only the melody line, chords and lyrics) and so on.
Anyway all these can be easily bought on Amazon. There are also special music stores like Musician's Friend, Sweetwater, Notestore https://note-store.com/ , Gear4music, Steve's Music Store, Best Music Co and so on. There are also many sites where you can download notes/sheet music for free so I recommend you to check them firstly.