1. Go to Marketing > SMS > Templates and click New Template.
2. Enter a Name (must be unique — you get "Template name already exists" otherwise).
3. Optionally pick a merge field from the Shortkeys dropdown; it is inserted at the cursor as a `{{...}}` placeholder.
4. Write the Message; the counter below shows characters remaining, message parts and cost per SMS.
5. Click Save.

Both Name and Message are required ("Name empty" / "Message body empty"). Templates are listed with ID, Name, Body and Creation Date. You need Edit Templates to create or change templates and List Templates (plus List Numbers in the current version) to open the list.