I want to have my letters fall and hit the plane, bounce and then land in order to spell words. How do I achieve this?
You can use a Rigid Body simulation to make your letters fall and bounce without having to animate them by hand - the problem is how to arrange so that they end up at the desired final positions when they come to rest. This can be achieved by Baking the simulation into keyframes and then adjusting the start position so that they end in the desired orientation.
Firstly start by creating your mesh - one way to achieve this is to create a Text object and use the 'Convert to Mesh' option to create the mesh (the objects need to be in Mesh format in order to be able to animate as rigid bodies).
Create the text object :
Convert to mesh by selecting the text object, pressing Alt+C and selecting 'Mesh from Curve/.../Text'.
Give the text some depth by either Extruding in Edit mode or by adding a Solidify modifier and clicking Apply.
Next, separate the individual letters by selecting everything in Edit mode, pressing P and selecting 'By Loose Parts', then select all of your letters in Object mode, select Set Origin (in the Tool shelf (T) or by pressing Ctrl+Alt+Shift+C) and select Origin to Geometry.
Finally, in the Physics tab set the selected objects to Active rigid body.
Make the floor a Passive rigid body to it will interact with the letters, position them above the floor, run the simulation, and they should fall and bounce.
Note : If any of the letters come to rest on the wrong 'face' you can adjust the simulation by moving the 'origin' further back into the object - this will make it's centre of gravity further back, resulting in it tending to be at rest on its 'back' face - this can be achieved in Edit mode by simply selecting all vertices and using Grap (G) and moving them forward in relation to the origin. Alternatively, just slightly adjust its start orientation and re-run the simulation and repeat until you get them falling in the correct orientation. If they collide, move them appart from the other letters to avoid collisions.
Now, to adjust the positions of each 'fall' we need to bake the simulation into keyframes - select Bake to Keyframes in the Physics toolshelf :
Once baked the simulation will no longer change. Run the animation to the end when all letters are at rest and adjust the positions by either adjusting the 'Delta' transform settings (this is applied after the keyframes so can 'offset' the location and rotation) or by adding an Empty at the same location as the 'at rest' point, parenting it to the letter, then moving the empty to the desired final resting place. Repeat this for each individual letter.
Finally, you can get more variation by delaying the animation on various letters (by moving the F-curve to the right in the Graph Editor) so as to give a more 'random' fall :