This tutorial will cover the primary animation method most people use to make great animations. We will animate a cube by placing starting points and ending points in a timeframe(IPOs)
I'm assuming you know how to navigate through the 3D-Space and the button windows. If you don't, then I suggest you should atleast read the Getting Started PDF included with Blender or read the manual.
Basics of Key-Frames
Open Blender. The defualt cube should already be selected. if it's not, then right click it while the pointer is over it. What we are going to do here is basically place a marker where the cube is currently. Then place a marker at a later time somewhere else to indicate that the cube should be here at frame 1 and then be there at frame 51. Press the (I-Key) to bring up the "Insert Key" menu. A Key is a marker that we will create right where the cube is. In the Insert Key Menu, select the "LocRot" button.

After you've selected the "LocRot" button. It has placed a marker of the Location(Loc) and the Rotation(Rot) So the cube is now locked in place at frame 1. Now press the (UpArrow-Key) five times. This will set the cerrunt frame to 51. Becuase the Up-Arrow key steps ten frames every time it's pressed. Now move the cube somewhere else. I moved it 5 grid units to the left. Then press the (I-Key) again and place another Key Frame.

Walla! You've made an animation! Press the (DownArrow-Key) until your at frame 1. Then press (Alt+A) to playback the animation. If you've done everything right, the cube should move from the center to wherever you placed it at frame 51. Also, if you select "Scale" or "LocRotScale" it will place a marker of the scale of the object as well.
Advanced Techniques
Again, if you are unfimilar with the Blender Interface, read the Getting Started PDF included with Blender or the manual.
After you've created you're cube animation, go to the IPO Curve Editor Window from the buttons window(Bottom header all the way to the left).
After you've selected the Curve Editor, it should look something like this:

Now, as the IPO Curve Editor is relevantly the same as the 3D-Space window. You will notice that it is possible to go to (Edit-Mode) in the Curve Editor. by moving around the different points, you are shifting the marker to different values. Go ahead, move some dots! Heres what I did.

After your done moving the points, play the animation and you'll see that the cubes rotation and location points start and end at different places. Now we are going to change the movement type. In the "Curve" menu, open the "Interpolation Mode" menu and then select "Linear" Then play the animation. You will notice a much harsher movement becuase it maintains an exact speed every frame. So you get a very solid result. Next go back to the same menu and select "Constant" This will switch the cubes position from Key 1 to Key 2 in 1 frame. So it will constantly go from Key Frames and not show any visible motion. Here is what they should look like:

Note: This is before I moved all the points to random locations.
Well, now you know all about Key-Frames. the next step when you get fimilar with the basics is bone Key-Frames and advanced Key-Frames from the buttons window.
If you're stuck or want to leave a comment, please go here: http://www.freewebs.com/lojimekworks/contactme.htm
Good luck and happy blending!