I just recently did this myself through godaddy.com ... and i'm THEE grand NOOB when it comes to foruming, believe me
🙂
depending on what forum hosting you go through, you may need to contact their support forum; and refer your title as something like "questions with Manual Domain hosting setup?" as long as the forum provider's support actually helps their members, you'll be good to go.
if you want a good laugh, here's my actual topic when i did this back in february ..
http://support.proboards.com/index.cgi? ... 199&page=1
through proboards, sadly i use them, i had to go through my godaddy account, and input 3 redirecting DNS server codes under the "manage domain account" to redirect to my forum.
it won't just redirect to your forum, it'll replace your original forum url, as well
🙂
I know i couldn't help, but just trying to reassure you, it's possible, cause if i was able to do it, ANYONE can. just check your forum providers support board. or maybe someone here will have more insight on the subject than i do.
good luck