It's a standard blues intro/turnaround.
Slide your middle and ring finger up to the third fret and anchor your pinky on the third fret e string.
Just like the tabs say. Use your index finger to barre the second fret and leave your pinky anchored
on the third. Just like the tabs say. Slide your index finger down to the first fret leaving your pinky
anchored on the third fret. Play open strings just like the tabs say and you guessed it leave your
pinky anchored on the third fret. Do a standard walk up on the A string 0 3 4 to and D7 chord.
Add funny faces for dramatic effect and practice, practice, practice.
If this doesn't help google Blues turn around there are thousands of them and they're all worth learning.