If you are just beginning with eBooks and do not have an eReader, try the free Kindle for PC program from Amazon. It is the easiest to download and use. Just 'Download now' then 'Run' this file. 'Accept' and you will be able to read eBooks. As long as you have an Amazon account it is as simple as three mouse clicks.
Download .mobi files and 'save' the file containing the book, before you try to open it.
If you are using Windows 8 or 10, download the Kindle for PC, not the App from the Windows Store. The App can only be used with books purchased from Amazon. If you are using an Android tablet see this note.
eBooks do not open themselves, you can only read them if you have the right software installed on your computer; so
1. Choose any suitable eBook reader program. (Available free from Amazon, Apple, Adobe, Sony, etc. - just Google it - there is a program available for almost every machine, in either format.) Then download and install it to your computer/laptop/tablet/netbook.
2. Download one of my free books from the shop. If you have installed Kindle for PC, Mac, iPad or Android, choose .mobi files - everyone else choose .epub files.
Your browser may ask you 'save or open?'. You MUST choose 'save', preferably, 'save as' so you can choose where you want it saved. If you are not offered the choice, your browser will have saved the file in your default 'download' folder.
3. Read, enjoy and, if you are not happy, try another eBook reader program. They are all slightly different, with more or less options and ease of use.
4. Try some free eBooks from other sites and see how poorly made they are compared to mine.
5. Come back here and buy as many proper eBooks as you can afford.
If you intend to read on an Android tablet please be aware that some lack functionality or are temperamental. You may need to discover where to store books on your machine, this is not always as easy as it should be. You cannot use the Kindle App from the Play Store, which only allows you to read books purchased from Amazon.
The easiest way is to use the ePub version of the book with Google's Play Books App. After you click the link to the book, select "Copy to Play Books", this will 'upload' it to Play Books. You then need to 'download' it from there onto your machine. This is a bit long-winded and takes a while, but it does work with most tablets. Experiment with a free book before you buy any.
If you are thinking of buying an eReader, there is some advice here.
If you are having trouble moving books to your eReader there is help here.