You can get information about most of the buttons in the app by hovering your mouse over the button for a couple of seconds.
Blue info buttons
You can get help at any time by clicking on the little blue info buttons, like below. This will then open a panel displaying the relevant section of this guide (good for when you forget what a feature works for).
The details of what you see may differ slightly depending on the version of the app you are using.
You can also usually get live help on these WhatsAp