[assassingod]

Ok, open newthread.php and find:

PHP Code:

updateuserforum($foruminfo['forumid']); 


Above add:

PHP Code:

if ($bbuserinfo[posts] < 20)
{
  eval("standarderror(\"".gettemplate("error_notenoughposts'")."\");");
} 


(You can change 20 to whatever number you want)

Creat a new template called 'error_notenoughposts'
with the contents:

You do not have enough posts to create a new thread.