Create your PDF file using a PDF maker of your choice. Most ebooks distributed from individual websites are in PDF format because it's still the most versatile. It can be read on an ebook reader or directly from the computer screen with an attractive format. If you have a package of multiple ebooks, put them in a Zip file using WinZip.
Give your ebook file a code name and write it down somewhere so you don't forget it. If your ebook is called Fishing Tips and your file is fishingtips.pdf or fishingtips.zip it's too easy for someone to go straight to the download page without paying for the ebook. Name it something like 8hezk4.pdf (or .zip). Pick something completely random that is impossible to guess.
Upload your ebook file to your website server. You need real web hosting for this, not a freebie site. Use your website control panel, accessed through your webhost. Follow your web host's instructions for uploading files. All webhosts are different.
Put your ebook in a folder in your file manager. Again, follow the webhost's directions on how to manage and use your file manager, because they are all slightly different. Put your ebooks in a folder named something like “ebooks” which will give you a directory to make the file download link. Your file download link will look something like this: http://www.yoursitename.com/ebooks/yourbookfile.pdf
Create a sell page on your website. Include information about the book as well as an image of it and how much it costs. Look around the net at other ebooks and how people are selling them. A great sales page will make the difference in many sales versus few sales.
Set up a payment processing area with sites like Paypal or Clickbank, so that you are automatically notified when payments are made and can send the customer the download link. Some companies will allow you to automate this process with automatic emails called autoresponders.