I think i understand what you mean. You need to add height: 100%; to both body and html style attributes and also add min-height: 100%; to your container div. That should fix it.
If your not sure how to do this. Go to Templates & Styles -> Themes -> Your Theme -> global.css and add height: 100% to both the body and html style attributes. Then find the #container div styling and add the min-height: 100%.
Can you please explain me in detailed
I've updated my first post, can you also provide a link to your forum?
i can find body attribute but there is not html and #container div
#container is definately there. You might need to make html yourself. It should look like this.
html {
height: 100%;
}
body {
height: 100%;
}
#container {
min-height: 100%;
}
Or something similar. It does work because i just tried it myself on your site. Its just a matter of you editing the code yourself.
http://i.imgur.com/Wqgg98x.jpg
i added the changes to global.css no changes

Looks fixed on my browser mate, don't know what to tell you... what browser are you using?
yea fixed thanks a lot

)
Np mate, good luck with your forum and thanks for the rep
