After selecting the first contact name hold down the CTRL key and you can select as many contact names as you like. All of these contact names will appear in the message recipient listing at the bottom of the page.
To get to either address book(s) from the compose SMS page select the Manage my Phonebook or Manage my Groups links. Both address book(s) will automatically open with "Last Used" listing. To get to other contacts either click "All" or search for them using the search field provided or the alphabetical listing.
To add a contact click the "Add to message" link, and this contact will appear in the message recipient listing on the compose SMS page. Once you have clicked this link the word "Remove" appears which you can click to remove the contact from the message recipient listing. Please note you can add more than one contact at one time.
This shows the contact names that you have selected to send an SMS to. Both groups and single contacts can appear in this listing. If you want to remove one of the contacts from the listing simply click on their name and they will disappear.