Before you begin working on your own animation projects, you'll probably want to consult a few resources. Consulting the literature about animation isn't completely necessary for the novice animator, but you can certainly learn a few techniques and get a few ideas by doing a little reading. One of the best books on the subject is Ollie Johnston's "The Illusion of Life: Disney Animation," which introduced the 12 basic principles of animation in 1981. In "Principles of Traditional Animation Applied to 3D Computer Animation," John Lasseter of Pixar revisits the 12 principles and considers them in terms of new animation technologies.
One of the easiest ways to create your own animation is through the use of puppetry. You can create your own sets and puppets using any number of different materials. You can connect materials together with thread, glue or tape. If you don't have any raw materials, you can produce shadow puppets by setting up a light source in a darkened room and forming your hands into various characters. When you've put together a show you're proud of, you can perform it live for your friends or record it with a camera on a tripod and upload it to the Internet.
Stop-motion animation involves moving objects little-by-little and taking photographs following each minute movement. It can be very time consuming, but it produces a really cool effect. One of the easiest ways to get started doing stop-motion animation is to find some clay and form it into a character. Set up your digital still camera on a tripod and don't move it. Take a photo, then move your clay character a few centimeters and take another photo. You'll probably want to plan for at least 10 frames per second in order to create the illusion of movement. That is, the distance you move your character, or a part of your character, will be how far your character moves in one tenth of a second. The best way to get used to doing stop-motion animation is to practice. Once you've got a few hundred frames shot, you can upload your images to your computer and scroll through them to see how they look animated. If you want to be professional, you can use editing software (Adobe After Effects, Stop Motion Pro, etc.) to make an actual movie file.
Another form of stop motion animation is called cutout animation. Just as with claymation, you'll be moving objects around and taking lots and lots of incremental photos of them. As opposed to claymation though, cutout animation involves flat images that you cut out from a piece of paper or tagboard. You can draw a character on a piece of paper, and then cut out movable arms and legs for him or her and then move these pieces to create a walking character. Again, you'll only move each piece a few centimeters for each consecutive frame in order to create the illusion of movement.
You can also create animation using computer software. Two dimensional animation can be produced with many different programs. Two of the most popular programs used are Adobe Flash and Adobe After Effects. In Flash, you can create vector images (shapes that you can enlarge infinitely without them taking on a 'pixelated' appearance) and set key frames to move them around. That is, you can set the location, size, and rotation of any object you make at any particular moment in time. You can create 'tweens' between the different moments in time and the program will automatically warp your images to make them flow smoothly from one set key frame to the next.
If you want to create three dimensional animation with a computer, you can use a program like Autodesk Maya or Autodesk 3dsMax. When you use 3-D animation software, you manipulate virtual three dimensional shapes and set key frames to move them around. You can create characters with movable limbs and virtual skeletons that determine he limits and styles of their movement and you can even manipulate the physics of a virtual environment to create realistic effects. You can create virtual light sources and add textures to your objects. Learning to animate in 3-D takes quite a bit of work but provides you with almost limitless animating capabilities.
While simply practicing and experimenting with animation techniques is a great way to learn how to create animation, if you're looking for more guidance or if you really want to devote yourself to learning animation, you may want to consider attending school to learn more and really hone your craft. You can consult the Animation School Database to learn about more than 900 schools where you can learn about animation. Animation Arena also has a list of some of the best animation schools for technical direction and character animation.