I agree with jsprogg. One of the biggest mistakes new people make, is to be over-ambitious. People that just start and say "I want to make something like the shots in star wars" will quickly burn out, and get frustrated as the software "isn't doing it properly", or something along those lines. If you wish to apply at Valve, it will take many years of hard work, as it's a very competitive industry.
With that out of the way, if you're willing to put in the effort, we'll gladly help guide you to your dream.
Again, welcome aboard. You'll like it here
Imagination is more important than knowledge.