My Style doesnt have Guest messege...
 

i know that somewhere on FORUMHOME template i should have
<IF condition="$show['guest']">

but i dont :/ i tried adding it at the header according to this article -
http://www.moderninsider.com/article54.html

but it gave me an error while trying to save the template.. that there is no such thing as $show['guest'] or something...

any idea on how i can add it ?

try this:

<if condition="$bbuserinfo['userid'] == 0">
code for guests here
</if>

thanks that worked.