The easiest way to add a module position to your template is by typing the new name inside the Positions field from your Edit Module View. For example, if you want to use the default "dinamod" position for your tab modules...

In your admin top menu, go to Extensions -> Module Manager and open each chosen module.

Initially, you should not see "dinamod" in the Positions drop drown list, so you will need to insert the new name by placing the cursor in the field just like in the illustration.