ok,
I think my japanese was not clear, sorry.
I made this

without python,
It showes what I whant to do.
I made a script, and on this script I add two constraints added to the camera, the first is a "Track to" and the second is " follow path".
I found on the internet exemples of "track to" that helped me to understand how to write the scipt code for the "track to" constraint.
my problem is that
I did find any exemple of "Follow path" script...
If you have an exemple, I will be glad to see how we write it.
thanks you for your really fast answer.