Importing a existing website done in Microsoft Expressions to Dreamweaver

"I have no experience with maintaining a website..."

In that case, maybe you should hire a professional to help you.  There's a good deal more to maintaining websites than just using Dreamweaver.

I don't know if lisaknit.com is the site or not but Ben_W is right.  A non-secure connection doesn't instill much confidence from potential customers.

Free SSL certs from Let's Encrypt or CloudFlare are probably adequate for the majority of front end facing sites where no personal data is collected or stored.  But where data and online transactions occur (your shopping cart), SSL/TLS certificates should be purchased from a reputable certificate authority.  Different certificates provide different levels of security and protection in the event of a data breach.

https://www.namecheap.com/security/ssl-certificates/

I had to look this up to be sure,  but the last version of Expression Web was back in 2012.  So it's been almost a decade.  If your website has not been through a major update, or at least minor refreshes since then it might be worth looking at redoing your website as opposed to just maintaining what exists today using Dreamweaver.

In just taking a minute to look at your site, you are running an ecommerce store, but the non-ecommerce part does not appear to have a SSL certificate. This can give mixed reactions to buyers as they enter through a non-secure site, but do eventually check out in a secure area.  It also does not appear to be responsive and websites that are not mobile friendly often do not rank as well because Google will potentially not rank your site as highly as one that is responsive.  Personally speaking, I would recommend looking at updating your site and not worrying about investing in Dreamweaver and rather, get someone to help you setup a CMS (Content Management Platform) that you can manage from the web without an expensive editor if you are not familiar with websites.

Setup a remote connection snd download (Get) the files to your local system. See https://helpx.adobe.com/au/dreamweaver/using/connect-remote-server.html

If you do not have the FTP details, get in touch with the host.