how should i build a game lilke amazing bricks in unity
You should start by clicking on the Learn link at the top of the page and going through some tutorials on how to use Unity. Also find some tutorials on programming and learn syntax and such.
look at this tutorial, It gives a step by step tutorial on how to make the game Here is the link It does work. follow through and you will make it. It is in unity 4.6 so you should be fine