In addition to text you will also want to add graphics to illustrate your topics. This tutorial shows you how to add ordinary graphic images to your topics from files and by cut and paste.
You can also use Help+Manual's built-in screen capture utility to capture images of objects on your computer screen and insert them in your topics. In addition to graphics you can also insert video files and OLE objects from other programs.
See Graphics formats and file size for details on choosing graphics formats.
Graphics files are the only project components that are not stored as an integral part of your project. However, you can put your folder(s) containing your graphics files in your project folder. This is also recommended.