htaccess 301 redirect assistance

[xAnacondax]

First off... I've been searching around trying to do my homework on how to do this, and I found an example, but I'm not confident I understand the coding well enough to customize it for my current domain. We moved our forum from a subdirectory (http://www.example.com/forum) to the root (http://www.example.com) and ever since we've had issues with ajax functionality on the board both with some built in features of VB and by extension those plugins that use ajax to function. Looking at my cpanel logs leads me to believe that the files/database are looking for that old directory and getting a 404 error. I wanted to see if there was an easy to understand resource that I can go by in order to set up a redirect from the old directory path to my current one and see if it fixes the issues.

Namely, how to enter the redirect properly in the htaccess file...
And where to put it.... whether it should be inside the root folder (http://www.example.com) or within the (http://www.example.com/forum) directory. Unfortunately I'm suddenly needing to deal with extrememly limited experience and I want to make sure I have it right the first time since I'm fixing a live website.


Any help would be greatly appreciated