There are two ways of creating a custom template:
Creating a Custom Template via the Build Profile Editor
To do this, you need to go to the build profile editor, and select Templates. From there you have to click the dropdown next to the template type you wish to edit, then select <Create New>. This will bring up the New Template dialog with the Base template already populated. Finally, you need to give your custom template a name and press OK. The custom template will be automatically selected in the build profile you have created it in.
Creating a Custom template via the Options Menu
You can also create a new custom Template from the Options menu (found on the Application Menu). You need to then navigate in the Templates section of the Options menu, and then click the Create New button in the toolbar, and select the relevant base Template. Once you have created the custom template, it will automatically be opened for edit. Note, if you create a custom template from the options menu, you will have to select your new custom template for use in the build profile editor after creation.
Editing a Custom Template
If you wish to edit a custom template that is currently selected in the Build profile editor, you need to press the Edit Template button next to your custom template.
If you wish to edit a template that you do not currently have selected, you need to navigate to the Options menu and then to Custom Templates. From there you need to select your custom template, and select the Edit button from the toolbar.