If you are working on an existing site, then you might want to remove the existing template, and if you used Page Includes save the path to the include at the top of the content when you remove the template for when you have attached the DWT and are selecting the paths to the Include Pages this helps you remember what they are.
Needless to say there are many other scenario's of an existing site.
Make a folder called dwt to store your dwt file in.
Normally when you want to create a DWT, you should start with a blank page saved as a normal page, adding your formatting with an embedded style sheet. NOTE: In order to maintain the relationships between a file and its attached pages Expression Web uses Metadata which is stored in folders which are hidden by default to prevent accidental deletion, or them being moved or changed.
Your editable regions should look like Fig 4, outlined in yellow (colour depends on the settings you have, the default being yellow) with the name of the editable region.
View Screenshot - Fig 4 - Editable Region outlines ATTENTION - I have outlined further information under the below headings you should pay particular attention to the Head Tags and Scripts if you want to retain your keywords and description Meta tags and any scripts for each page.
Next do the same for other editable regions you want, in my case I want an editable region for the menu on the left hand side.