signature

Hi, all! After how many posts my signature will appear?

I can't find where to add my signature for messages. Looked all over the Control Panel. Where do you set you sig?

I am not sure whether this post should be here or in seo, so I am putting it here. I want my signature to contain a link to my site, do I just do it when posting as I will try below, or is there a way of having a permanent signature link? thanks,