how do you get from termonal 2 to terminal 5 in Beijing International Airport?

Firstly, I think there are only 3 terminals in Beijing Airport. So what do you mean by teminal 5? Anyway, you can take the Cross Terminals Free Shuttle Bus in the airport to any of the teminals. You can board at T1 -- Gate3-5 on the 1st Floor; T2 -- Gate 11 on the 1st Floor; T3 -- Gate 5 on the 1st Floor.