Whenever I publish my site (which currently is only a single landing page, the index.html page), the software deletes my pre-existing "default.htm" page which contains my old site. I don't want the default.htm page deleted. Any suggestions?

Is the default.htm named default.htm?

put the files into a folder somewhere else on your server other than where you're publishing with VSD, that should stop that from happening

In VSD you can change the name of the pages that it creates. Just make sure, even if you only create 1 page, that you don't name it 'index'. Give it a name such as 'myindex' and then link to that page. To do this in VSD, create your page. Then click on the 'Page' button on the top menu. When the box opens on the right, change the 'Page Id' to whatever you want to name your page as. Let us know if you still need more help.

Thanks everyone for your response. I have tried naming the PageID to something else, but still the file on my server named "default.htm" continues to get deleted each time I publish, regardless of what I name the PageID of each page published. It appears to be a software issue which removes "default.htm" upon publishing even though the file created by VSD is named "index.html".

Try adding it to your site through VSD
"Edit" then "Add Files"