WinKey+PrtSc takes a snapshot of your entire screen (so make sure the web browser is maximized if you want only that - and it will include the tabs open in a given browser window across the top so if you really want only that website, open it in its own browser window before taking the snapshot).
You will find the resulting screen shot in your Pictures library, Screenshots folder, with a name of the format Screenshot(Number).png. The numbers start with one, and keep incrementing as you take screen shots. If you delete all the existing screenshots, the numbering will begin with one again.
Brian - Windows 10 Pro, 64-Bit, Version 20H2, Build 19042
One does not discover new lands without consenting to lose sight of the shore for a very long time.
~ André Gide