Or I am unable to see the website when I activated Dream Weaver that I have worked on so far. I am confused. Can someone help?
Not sure what you mean about being unable to see the website when you activated Dreamweaver, but the simple way to start the tutorial from scratch is to delete the files. Then replace them with a fresh set from the download zip file.
You can delete the files in the Dreamweaver Files panel. Alternatively, use the Windows File Explorer or the Mac Finder.
If you want to delete the site definition in Dreamweaver, select Site > Manage Sites. Select the site in the list that appears, and click the minus button at the bottom left to delete the site from Dreamweaver. Note, however, that deleting the site definition does NOT delete the files or folder that you created. It simply removes the site definition from Dreamweaver.