You would have to use the client-side programming to print a web page document. If you want to use the JavaScript, then this would work for you,
window.print();
The document in a web page form is already present on the client's system. Once this code would execute, it will display a print dialog to him, which he can then use to print the documents. You cannot force the machine to print, he will still have to press the "Print" button on his system, this would just facilitate him to see the dialog for printing the document.
MDN resources for window.print()[
^].