Since back in 1996 I became a member of Association of Shareware professionals, a lot has changed. At the time, a crowd of software hungry users were quite happy to send you money in the mail, in payment of shareware that was often fully functional, no nag screen, no limitation.
Today, the notion of shareware tends to be blurred, as even big software companies have demoware which, for all intents and purpose, quacks and walks like shareware.
The arrival of the App Store for Mac, and the Windows Store for Windows 10, have been an additional earthquake in the small shareware pond. Instead of paying the author directly, a lot of users prefer to go to the online store and buy directly from the big guy.
However, I can report that with the proper promotion, demoware/shareware can bring in sales to your web site, if you are able to offer immediate download. I enjoy actually double sales on my own web site for Check Writer III+, than in the MAS.
There are currently hundreds of download sites. Appvisor.com lists 620 of them, after screening them to make sure they are live. It is pretty impossible to be present on all of them manually. Although a search on google by “Download shareware” will probably result in skimming the top dozens of them.
Shareware repositories today expect you to pack a PAD file in the package, together with your demoware executable. If is an XML which contains a precise description of your program, its price, and which URL to go to to register (buy). Appvisor will let you create it for free.
Upload the Pad file to your web site, in the web area.
I strongly recommend, though, at least when you launch your program, you get listed by appvisor with their paying submission system. They will make sure the app is present on each and every software repository that caters to your type of program and platform. Since the Pad file can be updated when you issue new versions, they will keep current without the need to pay again for submission.