Sometimes radio stations give backstage passes for up and coming concerts. Otherwise knowing someone in the group would help. ALso if you work on a newspaper use your pass.
One way to get these passes is winning them through radio shows or contests. Another way is knowing the members of the performance you want to go backstage for.
Usually only by knowing and being friendly with the stars, or someone responsible for managing the show. Very occasionally, passes may be awarded as competition prizes, or auctioned for charity.
