Need some help with True Image

I have read the guide of the True Image already...I have even read it a few times but it seems that I still don't get it. I hope you guys could explain and tell me how to use it in detail. I used to have a true image installed in my PC, but I blew it. When I started my PC, the True Image word would pop up. But after my pc was down and fixed, it was gone and I do not know how to install and use it.