How can i migrate Bonita Studio 5.8 bar file into Bonita BPM 7.2 bos file?

I am currently working on Bonita older version 5.8, Now i want to work on Bonita BPM 7.2, so I am having problem to open my bar files into Bonita BPM 7.2. How can i open 5.8 .bar files in Bonita 7.2?