is there a way to set all url names with out the "www" (mysite.com for example) to be redirected to www.mysite.com?
example: if we type the url "mysite.com/contactus", this will be redirected to the page "www.mysite.com/contactus"
Not in Matrix. You have to do that at a higher level, like in Apache.
Yes, and the preferred way is in your Apache configuration, rather than in Matrix. If you need a hand doing this, search the forums – there was a very recent thread on how to do this.