You can use images in one of the following ways:
Step-by-step guides have their own topic, here we'll talk about inserting images into topics.
You are not forced to use Image Library, you can add images into topics as in usual text processor, using the toolbar button shown below.
Inserting library images is not very different from it. Click on a toolbar button and select an image from the drop-down list. Note that images are grouped by category.
Now when you change an image in the image library it is automatically updated in all topics that reference it.