I sell an ebook called Bullwhip Making For The Beginner, it's an ebook and some streaming videos. How I do it is they order via my site and then I email them a username and password to a page on my website where they can watch the videos and download the ebook. The password software I use is called Website Access Manager and you can learn more about it at: http://www.coffeecup.com/website-access-manager/
You do need to know how to upload things to your website to use this software, it's very easy to use!
Some people are worried about things like people sharing passwords, and here's some software that I use for another business's ebook I have where pirating is a problem: EbookPro This software is a bit more spendy, but you own it, so there are not extra charges besides the software. EbookPro will only let you set the number IP addresses that can be associated with a password. So if someone wants to read the ebook on two computers, they have to unregister it and move it to the next. So if they do share the password only one person can look at it at a time and you can configure the ebook to be printable or not printable.
I highly recommend either program.
Louie