A few questions about databases

Hey,
I had someone code my site for me, I'm a little familiar with html/css, but know nothing about databases and mysql.

My site lets people log-in via google, facebook, or by making an account for the site.
I'd like to add a phpbb forum to my site, but I have no idea how to merge/relate the databases so logging in on the site automatically logs you in on the forum.

So my question is... Is this something that I could read up on for an hour and get done pretty easily? Is it something someone else who is experienced could do for me in a few minutes? Or is it a difficult task that I'll probably have to pay a freelancer to handle?

Thanks for the help guys :)

I don't think the hard part here is the database merging that you 'd likely want to do.

It's more likely to be the PHP "session management" that you'd need to merge. That is, once a user does login, each of the two systems has some way of remembering that fact. Typically--but not always--this is done by sessions. So it might be as easy as changing the names of the session variables used in your existing system to match the PHPBB ones (I certainly wouldn't go the other way around).

And then you get to tackle the merging of the two databases. Again, how easy or hard this might be depends on how similar the structures of the tables are in the two systems. And, again, I would abandon your existing database in favor of using the PHPBB database. You surely have many fewer pages of code that will need changes than does the PHPBB system.

Is it hard? No. Is it tedious? Almost surely. Is it something you will figure out in an hour? Not unless you are psychic along with being a genius. A day or two? Maybe. A week or two? Probably.