User can send the bulk messages using Leads tab.
For this:
1. Click the Leads tab & select All Open Leads/Recently Viewed Leads/Today's Leads option from the Leads drop down on top left corner.
2. Select the desired Leads from where message is to be sent by clicking the respective check boxes.
3. Click Send Bulk SMS button on top right corner of the page under the blue downward arrow or directly click the same button in case the drop down is unavailable.
4. All related target phone numbers corresponding to the selected Leads will be displayed on the next page where the message will be sent.
5. Type the desired message in the message body then click Send button to send the SMS.
Success message will be displayed.
Note that same steps can be followed for sending bulk SMS from Contacts where user is only required to select Recently Viewed Contacts/My Contacts option from the available View drop down list.