I think you mean Newsgroups; they are not quite like chatrooms, but act in a somewhat similar way. There are about 100,000 newsgroups on a wide range of subjects, not all in English.
You need to know your ISP's newsgroup server address (usually something like news.ntlworld.com, but your ISP should tell you) or use a public newsgroup server such as news.astraweb.com
You also need a news client, i.e. a program which understands newsgroups. Whilst Outlook Express can do this, you might be better off with a dedicated program. My favourite is Forte Agent, a free program from click here
Start up whichever program you wish and first it will want to download the list of newsgroups carried by the server you select; then you choose the newsgroups to which you wish to subscribe and download what is called headers, e.g. the subject lines of posts. Then you can browse, respond or whatever you wish.