Read here or watch the video
Go to widget (Settings --->>WhatsApp)
Write your phone number (the country code will be added automatically)
Press 'Initialize'
Good!
Let's go to our Leads. Press 'Setup'
Great! Add a new source
Choose CRM Plugin
Make WhatsApp active (it will become green after you press on it)
Scroll down and text your website address
Do not forget to press ENTER
Then SAVE (up there)
Scroll down again and copy the CODE for the button
Just add it to any html block on your website.
If you do not deal with websites - ask your developer to add!