How to add data from old forum to the new one

I installed new version 2.0.3 of miniBB and it is running. There is hundred of posts in it. Some users ask me to add data from old 2.0RC4b forum. I have backup database file from old forum but I'm afraid that simply importing them using phpMyAdmin will destroy existing database. What you suggest me to do?
Thank you in advance!

During installation of new version of miniBB I changed table names, so I noticed that in MySQL database are old forum data with diffrend table names. I think it is only the matter of intgration with new tables? How to do it and not ruin existing data?

Read this topic as it could point you to the correct upgrading guides.

So far I could tell you don't need to import anything. You just need to upgrade the old database, adding new fields and converting their values with special utility described in the guides. Creating new database and importing data from the old will bring you a lot of bad surprises.

Our free support is very limited regarding upgrades, and if you are in troubles how to do that correctly we are providing only paid support.