Google keeps the algorithm a closely held secret. Many people have been able to guess at some of the general aspects of it. For example, the more back links the better. But the details are secret.
The best you can do is to visit their Google webmaster tools website. By reading their recommendations you can infer a lot about the algorithm. If they make a recommendation that means that their algorithm takes it into account.
For a general idea of how google works, you can read the original paper written by the creators in 1995 (
http://infolab.stanford.edu/~backrub/google.html). It gives a lot of information about the general workings of the algorithm. Google has made some tweaks to it in the last 14 years. But the basic principle remains the same.