Fender Play is one of the top Guitar self-learning programs online. They just teamed up with Metallica to add the band’s Top 10 Riffs/songs. You can sign up for a free trial, monthly or annual plans at the Fender Play website, and see a full list of Metallica tracks. The service adds new songs and collections weekly. 

Metallica songs added to Fender Play inludes:

Master of Puppets

The Unforgiven

Creeping Death

Enter Sandman

Fade To Black

For Whom The Bell Tolls

Nothing Else Matters 

One

Seek & Destroy

Welcome Home (Sanitarium)

https://try.fender.com/play/metallica/