www.wysiwygwebbuilder.com

There is someone who has experience with whatsapp on your website.

i use web.whatsapp for both personal and support purposes
but i'm not sure what you are trying to do... can you pls explain?

The intention is that those who visit my website to send a whatsapp to my phone (phone number).
Do not know if it is possible in Holland are the descriptions of the subject very vague.

De bedoeling is dat gasten die mijn website bezoeken een whatsapp naar mijn telefoon (telefoonnummer) kunnen sturen.
Weet niet of het mogelijk is in Holland zijn de beschrijvingen van dit onderwerp erg vaag.

whatsapp is an application installed on your phone
web.whatsapp is a page with a specific application
unless you have the same app in your server (scripts, rights, etc) i doubt you can send a whatsapp msg or make a whatsapp call

What you want is not possible at the moment. However you may install a chat system on your site that provides audio calls too, but this is not free.

a chat system on your site that provides audio calls too, but this is not free

even if you have that paid script and even if you have a paid hosting service, most of them won't allow you as per their terms and conditions (due to shared ip, limited use of databases, and other thingies)
this is not for freebies lol
you will need a hosting with i.e. webrtc or red5 support
those "scripters" who offer you the "solution" are using an external service (paid by you or paid by the call initiator)
if you still install such scripts without a special [paid] configuration, your hosting account may be cancelled
hope this helps

You could include a bit of PHP to send you an email?
E.g.
.
.
$mailto = "your@emailaddress";
$subject = "website accessed e.g.";
$message = "message\n";
mail($mailto, $subject, $message);
.
.
To avoid being bombarded with unwanted emails you would also have to test various server settings like $_SERVER['HTTP_USER_AGENT'] to exclude search engines.

So I assume you would want that for customer support? Why not use fb chat?