Totally lost. 

I pasted an image. 

Here is my list of try and error after then:

1. The image was far too large and I wanted to resize it by using a handle on the top left corner (the only corner I could see). It moved around instead.
2. I looked in the menu to the right of the screen to find some formatting options. Therein was a symbol showing the figure next to a “100%” without any explanation. So I expected this to be the size of the image and typed 25, to then see it become transparent and almost invisible. Ctrl-Z.
3. Then next, I did Ctrl-F to search for “size” and found nothing.
4. But now, the buttons on the right are missing.

I am afraid I have to tell you that Figma desperately needs some kind of introductury tutorial...