Hi @mouzaia,
When creating forms and posting using acf_form() the first step is always to create your field group and then assign it to the acf form through the $options array. In your case, you will need to create an image field to upload the photos for you. This field key can then be added to the acf form $options array in the ‘fields’ value.
You can checkout the docs here: http://www.advancedcustomfields.com/resources/acf_form/
