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Clicking the "Add image/media" button on the far-right gives you a variety of options to place non-text content into your page. "Image" will be most handy (for details on Image sizes/etc, see the Image size/crop requirements page).
A cool trick
But here is a trick that will make image management much easier. If you ever want to delete or remove an image, you can select it in the WYSIWYG view so that it's highlighted yellow, and then press delete:
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