Typically, Ashley will not have time to write this plugin... He is focusing to improve Construct 2.
Could you explain what is kind of file want to upload in the runtime?
There some developed plugins can upload images on runtime what it changes character player sprite to uploaded image by an user, but it's only for client side, not server...
Remind: Construct 2 is designed to make games, NOT webdesign. Just use HTML/CSS/JS on notepad, it's easy but you need to learn a lot.
This is best website it may you help to learn web development for free.http://www.w3schools.com/Joannesalfa2012-05-22 09:54:57