Simple tut go too [ Register or Signin to view external links. ] . worldofminecraft .com register and log in and download the WoM cilent and then get the url of the server you want or just log in at minecraft website and type in [ Register or Signin to view external links. ] . minecraft .net/servers.jsp and it should come up with a list and then click on one and then enter the url into the cilent and play.
EDIT: or just log in and then type in [ Register or Signin to view external links. ] . minecraft .net /servers.jsp that also works