Massive was developed not BY LOTR, but FOR LOTR, by Weta Digital, Peter Jackson’s FX company behind LOTR’s effects. This was a cheap and easy task by NO means. It must have taken TONS of knowledge and smarts to write Massive, which basically allows you to set behavior for thousands of characters, even based off of what is going on in the scene.
Anyway, start small if you don’t really know how after effects is used. I’d suggest googling “After Effects Tutorials”, and first getting a feel for the capabilities of the program. Then, you can start tackling fancy effects, etc. AfterFX is great for compsiting, 2D/2.5D animations, and motion graphics, but it’s not a 3D package, and you won’t be able to generate life-like 3D figures with it very easily.
For 3D packages, check out softimage xsi, maya, and cinema 4D to name a few.
Hope I helped a little bit…
Alexander Gao
“When the revolution happens, I’ll be leading it.”