Sorry I didn't reply yet. I have been away. You have to look gmail's SMTP settings up in Google or something.
Personally, I just made a new one with AOL, but that ends up going straight to the spam folder, so I am going to use gmail also.
Here, look at this: http://support.google.com/mail/bin/answer.py?hl=en&answer=13287
That shows you how you set it up, and yes it does use whatever email and password you use- so you could use your personal email, but I wouldn't recommend doing that. Make a new one for MyBB.
Hope this helps.
I saw your thread asking about PHP mail. It doesn't let me post in that section so I figured I'd just leave a message here.
It is much easier to set up the SMTP with gmail or an AOL email instead. I did the same thing with my MyBB setup. Just look up the email's SMTP server setup and use your forum's email (same one you use to install it).