three Indian ways to get there. 

1. Shared Autos.

2. Buses 

3. Private Cabs. 

Shared autos will take somewhat around 1 hour to reach there and they will not start until it is full. 

Buses you can catch from Amritsar Bus stand and there you must reach a bit early - 45 min drive + 30 min wait in bus. 

Private cabs are costlier, on which I traveled took 10 INR/km and it was around 40 km. 

The Ceremony starts about 5:15PM and you have to be there 15 min early to get a seat and atleast an hour early to get front rows. 
You have to add 10 min of walk from parking to ceremony place, so plan accordingly.