Try writing or pasting some text, then using the buttons above to format it. What happens when you select a different level of text on the “paragraph” dropdown? See what it looks like by pressing PREVIEW (on the right). This will open up a “user’s view” in another window.
Trying pressing ADD MEDIA (above) and see what happens. Select an image and try to make it sit where you want it to go.
Try pressing the TEXT tab (top right on this text area). This shows both the text AND some of the coding. Code is in brackets: < >. It’s used in pairs. <b> means start bolding text. </b> means stop bolding text. Anything text between those bits of code will appear in boldface.