Use the drop-down on the Owner, Tenant or Supplier list and select SMS (Text Msg.)
Make sure you select the person you're sending the text to. Make sure there is a mobile phone number in the MOBILE PHONE field and check that it starts with the country code prefix '+'.
Type in your message (The counter down the bottom will tell you how many characters and how many texts you are using).
You can select a group from the drop-down box if relevant (i.e if the text is about rent arrears you can link it to the rent overdue group)
You can also select a template from the drop-down box if relevant (You can set up templates for the SMS, these are ideal for SMS texts that you send regularly i.e your rent is overdue).