The file doesn't exist. Be sure that you have uploaded to the file to root directory of your site. If you have uploaded it to a different folder you need to have that folder in the address as well.
Thank you for your reply Brad. I am not sure how to upload to the root directory. I just created the htm file and uploaded it with my calendar. I am not very good at this. just following the steps that were given to me. can you help me further as to get to the root directory of my site?
Are you working in a defined local site folder? That's a critical 1st step for working with Dreamweaver.
Go to Site > New Site and enter a site name that makes sense to you.
Go to Servers and enter your site FTP log -in credentials and root directory. If unsure what to use here, contact your hosting provider.
Finally, expand your Files Panel and connect to your server. Ideally, your remote server and local files folder should be nearly identical. Check to see that your files are the same on both sides.