To type on a screenshot, follow these steps:
Click the Camera button.
Drag your mouse to crop a part of the screenshot that you want to send.
You can also take a screenshot of the whole screen:
...or upload an image from your computer:
...or paste an image from the clipboard:
...or acquire an image from scanner or a webcam:
To type into a screenshot, click on the "Type Text" menu, select the font, size and color and then click outside the menu window to confirm your selection. Now you can start typing into a screenshot: