I am sharing in this session method of creating background animation. You can peruse closely on the techniques that I deploy. I will show how I separate from one layer to the next and between background to foreground that I practice my tool of trade.

From the storyboard you can see how the came move from foreground to middleground. To create such a background I will have to separate many layers to ensure the the compositor has an easy task moving the camera.

I believe that the background mood that I choose to colour for this piece should be an evening peice. I would like to create a relaxed mood for the blue Baby Monster that is reading a comic. The use of colour is very important and I choose aqua blue and orange to increase the cheerful mood in this area.

The setup for the horizon line as you can see is an arrangement of hills using different depths of filed. The colour contrast has to be reduced to show that the hills have different distances.

On this layer I will start including the trees that are distant.

I start rendering more details on the middleground because the focus point of the camera is towards this particular area.

This is the process where I focus on colouring the baby monster. I will get matching colour on the surrounding background.

This is the foreground process that I will break into 4 separate layers to ensure that the camera movement can be easily carried out.

The final part is where you can see the entire background that is completed without the foreground.

credit to @zomagic