If you haven't read the section on timing and spacing in the survival kit, do it.
I'm going to animate a bouncing ball to figure this out better. Basically the ball will just bounce around. When the ball is contacting the ground is the timing, how it gets there is the spacing.
The book gives an example of a ball bouncing 4 times. One bounce it takes 20 frames, then 16 frames 13 frames and then 10. So I have my timing down, now I need to figure out my spacing for this. So first im going to set a key at frame 1, and frame 60. I click on the ball an
d press "s" to do this, I move over to frame 60 I move my ball to the opposite side of the screen and press "s" again. I know because my timing has been worked out I need 59 frames to get from point a to point b. So now when I press play I can see my ball travelling to this point, but theres no bounce. I want to change how it is getting there though so I open my "graph editor". This is under window, animation editors, graph editor. So with the ball clicked I can see a line there that represents the travel path. I drag my mouse over the line and change my curves to linear so the ball moves evenly spaced on this path. I go into the time slider and press "s" on frame 20 36 49 and 59. This exactly where I want the ball to be on these frames. 
Now I need to animate the bounce. So I go to frame 10 and translate the ball up in "y" axis to where I want the ball to peak on the bounce. I do this for all the 4 bounces I do, remembering the ball wont bounce as high on the following bounce. This is looking pretty ugly but its bouncing. So I need to work on my spacing now. I drag my mouse over the y curves and click the spline button, which flattens all the curves. I now need a key inbetween each key that will control the spacing, or control how the ball will get from the bottom to the top, and the top to the bottom. So I hold "i" on the keyboard and middle mouse click between each point to add the keys I need to control the spacing.
d press "s" to do this, I move over to frame 60 I move my ball to the opposite side of the screen and press "s" again. I know because my timing has been worked out I need 59 frames to get from point a to point b. So now when I press play I can see my ball travelling to this point, but theres no bounce. I want to change how it is getting there though so I open my "graph editor". This is under window, animation editors, graph editor. So with the ball clicked I can see a line there that represents the travel path. I drag my mouse over the line and change my curves to linear so the ball moves evenly spaced on this path. I go into the time slider and press "s" on frame 20 36 49 and 59. This exactly where I want the ball to be on these frames. 
Now I need to animate the bounce. So I go to frame 10 and translate the ball up in "y" axis to where I want the ball to peak on the bounce. I do this for all the 4 bounces I do, remembering the ball wont bounce as high on the following bounce. This is looking pretty ugly but its bouncing. So I need to work on my spacing now. I drag my mouse over the y curves and click the spline button, which flattens all the curves. I now need a key inbetween each key that will control the spacing, or control how the ball will get from the bottom to the top, and the top to the bottom. So I hold "i" on the keyboard and middle mouse click between each point to add the keys I need to control the spacing.So if I have my translate option on "w" in maya I can now select the new keys and move them around in the editor to control my spacing. I merely select the key I want to move, hold shift and hold my middle mouse button and move the key up and down, or side to side
. Up and down would change the height of the key , and side to side would change the frame the ball will contact that height. You can see how my curves end up looking after I have adjusted the "inbetween" keys. Also notice I the bottom tangents are red and blue. This means I have broken them. This allows me to grab one half of the tangent and pull it around without affecting the other half. Which is really helpful for a bounce like this. To move the tangent around, just select the side of it you want to move, and middle mouse click and move it around to where you want it to be.
. Up and down would change the height of the key , and side to side would change the frame the ball will contact that height. You can see how my curves end up looking after I have adjusted the "inbetween" keys. Also notice I the bottom tangents are red and blue. This means I have broken them. This allows me to grab one half of the tangent and pull it around without affecting the other half. Which is really helpful for a bounce like this. To move the tangent around, just select the side of it you want to move, and middle mouse click and move it around to where you want it to be.Here is the video of the ball bounce.
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