Thank you for writing in, you can use the Image element in Cornerstone to insert an image. But if you need to insert the image along the text line, then you need to use the html tag
<img src="IMAGE URL HERE" /> to insert your image inline with the text.
Please watch the video here, this should provide you an overview on how Cornerstone works. You might wonder why some of the Cornerstone's tools on the video is on different position, that is because its a lower version. But you'll get the idea how to utilize the Cornerstone.