There are many programs that will create an eBook but some are quite expensive.
If you are looking for an affordable program to use Open Office is free to download off the internet. This you tube will show you how to use Open Office and will supply a few helpful tips.
Once you have your eBook set up in Open Office you will need to turn it into a PDF (Portable Document File).
The one advantage of Open Office is that you can use this program to create a PDF. There are PDF programs that you can also buy but some are quite expensive.
Another advantage of Open Office is that the hyperlinks work well in the final PDF. This is not so with some of the free PDF programs available online.
This you tube will just give you an overall feel of what steps are needed to complete an eBook. What software programs you choose will depend on what you already have, your budget and what works best for you.