In your code, you are programming the frequency and the duty cycle of PWM channel 0 several times...
If you want to start 5 PWM pulses at the same time(e.g. PWM channels 0, 1, 2, 3, 4), once you have selected the right values for each PWM_CPRD and PWM_CDTY, you enable all 5 channels:
PWM->PWM_ENA = PWM_ENA_CHID0 | PWM_ENA_CHID1 | .... | PWM_ENA_CHID4;