Create a local site. Use the define sites command in DW3 and click new. give it a name and tell DW what folder you will be using to store all your files.
File structure:
You must test your work constantly in a browser. Open a browser and say open file and find your index.html file. Do not use the preview in browser command in DW3, it is unreliable.
Common to have index.html as your first page name.