From the sidebar:
Click on “Templates” on the left sidebar
Click “+Template” (upper righthand side)
Create your template, filling in Text (SMS), Email and/or Voice content.
Click “Save Template”
Your template will be available when you compose an individual message or a group message (formerly campaign) and will be private unless you choose to share it with your team.
** You can also create message templates prior to sending a message by clicking "Save as template" while composing a message