upload file inside a form html

I want to create a form to submit a product which has a features to upload images inside the form.

my difficulties are :

1. I find it hard to upload files without losing data that already fill by user in the form.


2. I want the user upload the file first then user presses the submit button

this is the sequence :

user open addProduct.php-> then the user fill the form -> the user upload picture -> finally the user press submit button to save their data