Make sure your ebook is compatible with all platforms and use PDF and HTML formats. I know my Macintosh can create a PDF on the fly without any extra software, I'm not sure about windows. If you really get into it, Adobe has Acrobat where you can add headers, footers, insert items, etc It's been real beneficial in our business but it's pretty pricey so if you don't want to spend the money, wait until your first PDF gets some profits rolling in.
I know of a variety of sites and catalogs where you can list your PDF file for sale. email me offline and I'll send them to you.
Rebecca