Add data with Separate Form toi Collection Restaurants

[MarGer1962]

Hi, I have this question. I have a separate HTML file which contains a form. Then - if the form is filled in and you click on submit - the data should be sent to the the firestore > restaurants collection.

I have a copy of the form included. HTML-Form code.txt I do not understand why i can't get it to work. Can some one help me out? (maybe to give me a link to a tutorial about this?or a publication?)

Thanks in advance