Use the edit button, you don't have to make 3 posts in a row.
If you want to take a screenshot, press the Prt Scrn button, go to paint or any other program like that and press ctrl + v on your keyboard so you get the picture. Now go file - save as - name, file type .png if you're using paint.
The prt scrn just copys the screenshot to your clipboard, so if you copy any text after pressing it or restart your computer, it will disappeare, so be sure you paste it to paint right after pressing the button.