If you have upgraded your account for LE beta, you should be able to see the LE forums at the bottom of the regular AO forums.
According to Nophex, upgrading your forums account should take up to two hours but could also be done in a few minutes.
If you can't find the forums, try this direct link:
http://forums.anarchy-online.com/forumdisplay.php?f=425
Of course you need to LOG ON AO FORUMS with the name corresponding to your upgraded account for beta to be able see/use those new forums.