Im a new user of Microtik , and just im trying to aply the examples of clients (http://wiki.mikrotik.com/wiki/API) to my router buy i dont know where i have to write that code.. thanks for your help

You can write a code even in the notepad

If you mean how to run python example, then go to
http://www.python.org/
download and install python.
Copy example code from wiki to file "api.py" and execute it

are you even sure you need to use the API? that's very advanced stuff

thanks for your help... yes i have to use that api...

as you were told on another thread, API is for controlling RouterOS from a remote Windows/Linux PC, not for using on the RouterOS itself.

I think you misunderstand the purpose of the API system.