My family operates a small retail fashion busines that is entirely a brick and mortar operation(a neighborhood store with no internet presence at all). I am not very technically experienced myself either, at least I have never designed a web page. I am interested in helping them establish some ecommerce capability for as minimal an investment as possible. Does anyone think it would be realistic for me to expect to be able to create a basic functional website to display items, offer them for sale, and accept payment by credit card and/or Paypal, on my own using a WYSIWYG program like NVU?

No.
Programs like NVU and DreamWeaver are made for creating web content, and little else.

Putting together an e-commerce website is more than just html; it is a complex system of dynamic page generation, content management, data management. Your best option would be to look into some ready made packages and try to adopt them for your own needs. You will, of course, need a server capable of handling your particular needs, or rent server space that will handle the same.

Suggesting you do it yourself would be completely irresponsible.

Thanks Groovicus. By renting space, I assume you mean a hosting company, please corect me if I am wrong. It was my intent to do that all along. Could you or someone suggest some ready made packages. By ready made packages, do you mean ones that I can use myself? I do have a do it yourself bias and like learning new stuff.

Yes, I meant a hosting company.

I appreciate that you have a do-it-yourself attitude. E-commerce websites are sort of special in that there are huge liabilities associated with running one; when one is dealing with credit card information, etc, there is an enormous responsibility to make sure that private information remains private. Going with a pre-established package helps limit that liability, especially since you will have (at least theoretically) some sort of support staff to help you set things up correctly. Choice of a host also becomes an issue when choosing whom to handle the store. $15 a month might sound like a great deal, but if the hosting company does not have the expertise to keep their systems secure, then any breach of privacy will become your problem. The ability to demonstrate that you have taken all conceivable precautions will limit your liability, and ignorance is not an excuse.

So that said, firing up your favorite search engine and looking around will probably yield plenty of ready-made packages, both commercial and open source. I can not recommend any because I develop my own for on-off use. I also can't recommend any hosts either because I do my own hosting. If I am going to get my butt in a bind, it's going to be because I made a mistake, not some faceless shmoe that failed to do their job properly.

Lot's of people have e-commerce websites, and chances are that you will not run into any problems, so this is more of a cautionary note than anything.