Second Step

Right, the next stage is to get everything ready for the animation. We're going to want to get the camera angles just right so that we get the illusion of perspective and distance when things are moving. The easiest way to do this is with a reference point. Try and find something relatively geometric. In my shot we're going to use the sign in the background.

Make sure the Polygon shelf is selected

then select the polygon cube tool

Now, using a combination of the move and scale tool you should be able to position it in about the right position over the sign

Now, obviously we can't see through this. It's hard to match up something we can't see through.
So! Go to shading>x-ray

And now we can see a little better how we're measuring up.

Now we can start tweaking to make it just right. This is where it really helps to know the camera settings of the footage you're using, but if you don't you can just guess to get it about right.

So you're going to want to select your camera again (window>outliner>camera1) and then click on the channel editor button on the top right if it's not already there

The one on the right here

Now the only thing we're going to worry about is "Focal Length". It'll be about 35 by default. Basically the lower this is the more extreme your perspective is going to become. In my shot it doesn't need a particularly dramatic change, buy you might need to tweak it a bit more in yours. I'm going to put it at 30. Now it looks like this:

Next thing we do is block out the objects that are affected by whatever you're putting in the scene. In my scene we're going to have the character looking out over the board, so we can block that out. We'll also put in a ground plane because he'll be on the floor and casting a shadow.
So use the various polygon tools to make whatever you need and have it match up as closely as possible with what you see in the scene. It's not necessary to create what isn't affected by your object. You're going to want to model from the perspective view so as not to mess about with the camera position, so go panels>perspective>persp.
Here's what I've done:

You'll notice a couple of things with this. Firstly I've not modelled the right hand side. As I said, that's because our character isn't interacting with that object. Secondly you'll notice that it's a little rough. You don't need to worry too much about detail here. These objects aren't even going to be visible in your final shot. Also notice that I've blocked everything out on the flat. There should only be slopes and angles in the blockout when there are slopes and angles in real life, that way the shadows will all fall in the right place.