configure rooms for MUC in ejabber

I want to configure rooms in ejabberd server

 1) Create Two Rooms with a Room Name by configuring ejabberd's config file
 
       Room Names will be 1) visitors 2) native

 2) Don't allow users  to create room    
 3) User can join any room those are configured over ejabberd server

Once the user joins the room either visitor or native they can chat to other user one to one

so far i have configured following values in **mod_muc**

    {mod_muc,      [
                      %%{host, "conference.@HOST@"},
                      {access, muc},
                      {access_create, muc_admin},
                      {access_persistent, muc_admin},
                      {access_admin, muc_admin},
                      {max_room_id,2},
                      {max_room_name,2},
                      {max_room_desc,300},
                      {default_room_options,
                      [
                       {allow_change_subj, false},
                       {allow_query_users, true},
                       {allow_private_messages, true},
                       {members_by_default, true},
                       {logging, true},
                       {title, "Visitors"},
                       {anonymous, false},
                       {persistent, true},
                       {public,true}

                     ]}
                     ]},
      {mod_muc_log,[
    
                     {access_log, muc},
                     {cssfile, false},
                     {dirname, visitors@mydomain.com},
                     {outdir, "/var/lib/ejabberd/muclogs"},
                     {timezone, universal},
                     {spam_prevention, true},
    
       ]},

i am passing following values from client interface of strophe

    JID : user@mydomain.com
    Password: userpassword
    Room: visitors@mydomain.com
    Nickname:user1

note: user is already registered on mydomain.com

but i don't know where to specify two room names and configured them separately in the file
as rite now i am getting "Conference room does not exist"

please do help