Question on dns and name servers
HiI just typed up a whole message with a screenshot, and it lost it all because it said can not post links when below 5 posts

anyway,
I totally dont understand dns or name servers, I am a experianced network administrator, web site designer and more, but the technical side of websites is new to me.
I registered tons of domain names with godaddy, and I am happy to use their online dns server, it works fine but I have a server, and would like to use it. anyway, they have a dns fowarding option, but I have got no idea how to use it. the link to the picture is ht tp://81.106.40.10/dns.jpg (i am hoping it will allow me to post it like that!)
anyway, they are currently registered to the parked page nameserver. I have no ida what this means, apart from it all works.
anyway, I really dont understand how to set up my own nameserver because I dont know the first thing. I just need a guide on how to start it up.
also another little problem I have is that my server is hosted on iis. I want to start a forum site, but it is in php. I dont really want to install php to iis so I want to install apache. On dns I can only get it to foward based on ip, and not ports, is there anything I can do install apache and let it run on port 80 on a subdomain, I want forum.site.com
anyway sorry if i am being confusing, but i really need as much help as possible.
thanks