Path finding / a* / shortest distance still a problem.

I have used path finding code made by others. I still do not understand how a complete path finding routine works. I have made partial working route planning by myself. This I did by looping thru all elements(all combinations) and finding the shortest one from point a to point b.

I am looking through a book on google books called "programming game ai by example" but it is in english and is difficult to understand.