Intro
I don't think there's any single right method to play this riff. 
Basically you play the A minor chord only with a change every other beat, 
where all you do is hit the 3rd fret of the 2nd string with your little finger. 
That's how you'll hear that change in the sound of the chord. However, I have 
tabbed it down as simply as I could. Remember to strum this chord upward as well 
as downward in a rapid action.
 
Riff 1

Guitar 1                                        
E|------------------------------------------------------------------|
B|--1--1--1--1--1-------------3--1--1--1--1-------------------------|
G|--2--2--2--2--2-------------2--2--2--2--2-------------------------|
D|--2--2-----2--2-------------2--2-----2--2-------------------------|
A|--0--0----------------------0--0----------------------------------|
E|------------------------------------------------------------------|

Intro Guitar 2
E|------------------------------------------------------------------|
B|------------------------------------------------------------------|
G|-7b9--7p5\4---2h5p4--2h5p4--2h5p4--2h5p4--2p0---------------------|
D|-----------------------------------------------5/7----------------|
A|------------------------------------------------------------------|
E|------------------------------------------------------------------|

Play Riff 1
Hai Jazba Junoon to himmat na haar
Hai Jazba Junoon to himmat na haar

Riff 1                G       Am
Justujoo jo kare who chhooai aasmaan
F               C       G                       Am
Mehnat apni hogi pehchaan kabhi na bhoolo
F           C
Sabki Nazron mein
E  (let ring)        Am  Am  C                         
Pakistan kabhi na bhoolo
G                   Am    Am    C
Pakistan hai tumhara
G                   Am  Riff 1
Pakistan hai humara

Am    C         G   F
Apna ghar apni sar zameen
Am       C    G    F
Sab kuch hai bus yaheen
G                         E
Itna to hai humko yaqeen