I have read through the entire official document on creating web files. But no where in that article does it actually guide us on "uploading" a file from our desktop into the project environment." Or maybe its said in a way I am not understanding.
Within my Portal Management area, I clicked on Web Files. I then clicked on New. And it brings me to a page that looks like this...

There is no input field on that page that says "upload".
I would like to upload a .css file, a .png file, a .js file and some other assets, so that I can reference them in my content snippets.
Whats the process?