Adding share with (whatsapp, telegram) in my current project ASP.net vb.net and SQL server

I already programmed a project in ASP.net VB.NET, i would like to add share button to share pdf file or text message with whatsapp number of my customer. Also, if we are able to do automation in whatsapp, if cutomer send invoicenumber then directly will share the invoice or share testmessage if invoice no completed.