Is there any way i can add a chatbox to my forums
Yes, just paste the code - $CHAT_BOX$ - into the place where you want it to appear. However it won't work on non-uCoz forums. In this case you need to use third-party chat scripts.
how do you attach a already made forum to your website
Just add the link to your custom forum to the site menu (the user databases won't be the same).
I'm not active on the forum anymore. Please contact other forum staff.