I've used the circuit of colpitts oscillator and add one capacitor in series to inductor to make it Clapp... this is the link of the circuit I used.
http://how-to.wikia.com/wiki/How_to_build_an_oscillator_circuit

I hope you can help me. THANKS

 

what help do you need? explanation of Clapp oscillator operation? like all oscillators it is an amplifier with positive feedback. oscillatory circuit sets the frequency of oscillations. positive feedback is obtained through C1:
http://en.wikipedia.org/wiki/Clapp_oscillator