PWM example to generate 20microsecond ON and OFF at LPC 1768

[Chandrasekaran]

I want to produce 20 micro second ON and 20 micro second OFF (total 40 micro second)PWM pulse at  LPC 1768 output pin. I want to know how i can config pin as PWM pin and set 20 micro second ON ,OFF cycle. Also i want LPC 1768 sdk zip file to import with MCU xpresso IDE and example