Domain Name Confusion

Right, lets see. I own a website, and a domain name, it is www.pitbullclan.eu. I want the domain of my forum to be something like www.pitbullclan.eu/community.htm or something similar but I don't understand how I go about doing this? Any help would be much appreciated, and, if you know how to do this, please give me it in precise detail. I'm not a web genius and big words can throw me off.

Thanks.

PS: Forums are well tidy.

This is the Forumotion support board, not Freewebs.

The domain works fine for my site, im not asking about it.

Its the following that I don't understand. I need it further explained.

When you choose the sub-domain which you wish to use on your forum (forum.my_domain, for example, is a sub-domain of my_domain), you have to create the corresponding CNAME entrance in the DNS administrator of your domain: a CNAME entrance allows to point an url towards the other one in a transparent way. in this way, you can link forum.my_domain to adress.my_forum.

Any recorder of domains names possesses different interfaces, and thus different methods to create such CNAME.
However, in a general way, the process takes place as follows:

•Connect to your user account on the site of your domain name provider, and go to the DNS management.
•Check that the chosen sub-domain is not already used.
•In the generally entitled field "source", "origin", or "alias" enter the prefix of sub-domain (i.e. "Forum" if you want to use the sub-domain forum.my_domain).
•In the generally entitled field "destination" or " target host ", enter the original url of your forum, adress.my_forum.
•You will maybe have to inform the TTL (Time To Live): give the maximal possible value.

Ya waaaa?