Thanks smftre, in fact, when we make a subdomain, it builds its httpdocs dirctory, and it will not be easy to a normal directory in the httpdocs of the website, non ??
Also a question, do you think that possible to have the website on a sharing hosting and a part of the website, who gets a lot of traffic on a dedicated server ? if you ask me wy ? because when this part of the website ( the forum of the website ) get a lot of traffic whole the website go down.