Added contact form fields not appearing in the sent email

Hi,

I have managed to add more fields to contact page (http://breweleasing.pl/?page_id=160), but they do not appear in the email when I submit it.

Could you please help me and tell how to make it work?

I am not a coding master, rather amateur, but here is the example of the code for adding fields:

< ?php _e('Przedmiot leasingu', 'Aqua'); ?>*

Much appreciate your help!