This riff is great for beginners to learn, yet may still provide a bit of a challenge for more intermediate players, too. The basic premise for the riffs is 4 chords played arpeggio style, or in other words: one note at a time. You’ll want to let each note ring as long as you can.
Once you learn how to finger the chords you should practice switching effectively between them. Once you are able to play all four chords with ease you’ll be able to work on playing them one note at a time. Playing the chords in this arpeggio style is the hardest part of playing the riff.