Walls is a sweet song played on scale of F, I’ve found a lot many chords, tabs on the internet but the riff played at the end of the song, so here it is…

Hold the F chord position, with ring finger on 3rd fret on F, the middle finger on 2nd fret on A, the index finger on 1st fret on C. Keep the little finger hanging..

e|-------------------|-------------------|
b|------1-------1----|------1-------1----|
g|----2---2-3-2---2--|----2---2-3-2---2--|
d|--3----------------|--3----------------|
a|-------------------|-------------------|
E|-------------------|-------------------|

When u play the 3rd fret note on G string (Bb), use your little finger to fret it and keep the rest of the positions the same. Keep playing that riff till the end.