If it sounds like a lot of work, you're right. Fifty animators worked on the movie Dinosaur. It took over 70,000 CD-ROMs to hold all of the information they used and over 3 million hours of computer time. But they learned a lot and ended up with a fantastic result. The fun is in the creation and being able to make the animation come out just right.
Most people learn computer graphics before they get into animation.
If you can show a lot of good animations that you've done, you can get a job. But, to get really good, you should take some courses or get a degree. There are 2-year programs with courses like computer character design, gaming design, shading and lighting, motion study, and 3D. Some animators have college degrees in computer science or fine arts. If you're interested in computer animation, you can start by working with computer graphics. At school, look for multimedia and computer programming courses.