Upload file box functionality

Hello all,

Grav newbie here.

I just started to play around with grav and i am using a skeleton-type theme (Agency theme).

Now to my issue.

I am trying to put a “upload file” box in this page https://demo.getgrav.org/agency-skeleton/#portfolioModal1 as shown here https://learn.getgrav.org/forms/blueprints/how-to-add-file-upload
but with no luck.

the specific page .md file is :

title: Portfolio
menu: portfolio
- title: Web developer
subtitle: Website Design
layout: default
modalid: 1
date: 2014-07-18
img: dreams.png
thumbnail: dreams-thumbnail.png
alt: image-alt
projectdate: April 2014
client: Start Bootstrap
category: Web Development
description: Lorem ipsum dolor sit amet, usu cu alterum nominavi lobortis. At duo novum diceret. Tantas apeirian vix et, usu sanctus postulant inciderint ut, populo diceret necessitatibus in vim. Cu eum dicam feugiat noluisse.

any thoughts ?