This is the intro riff to the Beatles song "Birthday".
The riff plays for 1 bar and 1 beat ( count 1 and 2 and 3 and and 1 )
You then have to count three beats of silence before playing the riff again.
Count - 2 - 3 - 4. On the soundfile I have put in a hihat on these beats.
Note that the last note of the riff is a stopped note - you have to pluck the string and then touch it with your finger to stop it vibrating.
Once you have learned the riff on the first pair of strings (strings 5 & 4) you simply move across to the next pair and play exactly the same sequence.
Use all upstrokes with your right hand.
Use a finger for each fret with your left hand starting with your first finger at fret 2 - so your third finger gets all the notes on fret 4 and your fourth finger gets all the notes at fret 5.
Don't try to run before you can walk - practice SLOWLY and methodically until you have the sequence of notes firmly established. Then speed up gradually until you can play at the tempo of the sound file