You need to configure a news server. Your isp should provide one(if you have
one configured it may be due to a malformed news url, but I don't know the
format for one). Look up how to subscribe to a news server and then
newsgroups with outlook(should be in help).
To add to what Daniel said. The microsoft newsgroup server
(msnews.microsoft.com) does only contain the microsoft.*
related newsgroup and not other public newsgroups. You will
need to use some other server which does, like a newsserver
provided by your ISP.