Working on a Harry Potter RPG, need help

[Kurvos]

Ever since I started to work on maps years ago, I've from the bottom of my heart wanted really badly to one day make a Harry Potter RPG. And finally, I've managed to find models to go with it through this video on Youtube: https://www.youtube.com/watch?v=M5yULz6OZSE
But the problem is, the models are impossible to use the way you use downloaded models through this site. Apparently, you need some form of software where you work on models and such through which I don't have. Heck, I don't even have something as simple as Photoshop. And I'm not the smartest guy, I don't know how to figure these things out. It took me a very long while to just understand how to alter things in the WC3 map editor.
What I specifically want are the models from Prisoner of Azkaban to work (links to downloads in the description of the video). Of course, the others would have been nice too - especially for the dragons. Apparently, the animations are already all set for it to work. I just simply am incapable of making it functionable for my Harry Potter map to work on through there. I've tried really hard to find other alternatives for it, but I haven't succeeded to do so.
Can someone please help me? Only things I could give you in return for helping me out would either be to draw something for you I'd post on DeviantART, since I'm an artist there: http://kurvosvicky.deviantart.com/
Or you could tell me what to do in my next Merlin sketch on Youtube, since I'm dressing up as Merlin there for silly videos for the sake of entertaining people and make them laugh: http://www.youtube.com/playlist?list=PLx60flPcH6wJEAmCEKYxYJBj8_L_hbKD1

I wish I had any money to offer you, but I don't. >_< I'm just a modest guy who wants to be able to work on a Harry Potter map... and I thought I was so close when I discovered this video, and it broke my heart it turned out that wasn't true.

 

[nGy]

Those models are ripped from other games, which means, it's against THW rules for anyone to help you here (not that I could anyway ). The ".mdx" extension is pretty much Warcraft 3 specific; 3d modelling programs tend to use their own extensions.
However, something I can say from personal experience: Try not to have such ambitious dreams or at least clearly distinguish them from actually achievable goals. Sometimes it's best to just acquire a skill, that is needed to reach your goal, because it can help you get an impression of what realizing that goal means and adjust it accordingly.