Hold down an open E minor chord and you're ready to go with this simple riff.
The excercise here is in alternate picking - your right hand has to go down up down up etc. throughout the riff.
To achieve this start slowly, making sure you're hitting each note evenly with the correct up or down stroke, then gradually speed up until you can play at the tempo of the soundfile.
These are eighth notes - count 1 & 2 & 3 & 4 &.