There should be an “Edit my Post” Link on the bottom right of your posts. At least for me it is there. Please have a look again and tell me if it really isn’t there for you (And if it’s not please check if you’re logged in while viewing your post).
That’s weird… I just made a test account and had no problems post editing a posting…
I did have problems with logging out of my real account though, somehow Firefox seems to have problems with sessions or something of phorum.
No idea why it doesn’t work for you, sorry. Maybe log out and then log in again.
Is anyone else having the same problem?