my instructions are probably confusing so just go to the help desk thread and there are some pinned threads that should help youto add a picture you have to click the icon that looks like a a picture on the menu above where you type. It's in between the chain and the smiley face. If the picture is from online then you click the little chain thing, then you copy and paste the image address, not the link address. If the picture is on your computer drive then you click the little arrow thing, then you can select the file you want.
to add a video you click on the icon in the menu that has 3 dots, and then you click media. Then you copy and paste the link address where it says enter url.
to add a quote you click the same three dots but pick quote.
Let me know if this helps, and if not I think @Key posted a guide to it in the help forum