Windows Can't import maps to server files

I recently rented a server from https://gshost.us/server/view/id/241 Which was recommended by the main Kag site

And I want to host a war server (since no-one else seems to be) But it turns out that War isn't an official gamemode, and so it has no maps pre-made for it. This wouldn't be a problem if it wasn't for the fact that I cannot figure out how to import maps. For those who have never rented a server from these guys, you basically have a page showing you loads of settings and information on your server. There is also something called the "Quick File Manager" which is what you use to browse the server files and edit them. However, you can't download these files or add new ones, you can only change the ones that are in text form.

So when I downloaded a few War maps (in .png form) and tried to drag them in with the others, nothing happened! Am I supposed to add maps somewhere else? Is there something I'm missing? Or am I just being stupid?

Any help would be greatly appreciated, I don't want to spend £4.58 every month for no reason :(