First add the image into the Cascade system. Next navigate to the desired page, choose edit and position the cursor where the image should be inserted.

An "Insert/Edit Image" window will open.

Select the browse button to open the "Chooser" window, select an image from the imx folder and select Confirm.

The image file name will appear in the "Insert/Edit Image" window. Fill in an Alternative Text area and select insert.

Distinctions between internal and external images
External images are those stored outside of the Cascade system and referred to by their htttp:// address when they are placed on Cascade pages. Since externally stored images are on someone else's web site and can be modified or deleted without notification, using external images is not recommended.
Additional information on adding images can be found here.