How to incorporate parts of a database?

[theforumist]

Well, my archived database was being a pain in my ass when I tried uploading it, so I eventually gave up. I'm planning on doing a clean install and starting new. Lets say I would like to include some of the forums on the old database along with the topics and posts in it? And what about members? Is it simple copy and paste? Or do I have to go all tech nerd on it?

Also, where in the old db would I find the stuff, and where would I add it to the new db?