You can make different screenshots.
For whole window screenshot just press PRTSC button for 2 seconds.
For last opened window use ALT GR + PRTSC.
Open paint and use CTRL+V and saved pic will be shown. Just save it as jpeg file and job is done.
For doing screenshots you can use some third part application. Google a little bit and you will find a lot of them for free download.
I completely agree with Mores… Very good description.
If you made a screenshot with PRTSC button you can paste it in every picture editing program, for example Photoshop, Paint Shop Pro or something else. Then you can also add the date for example or something else.