Toggle OC1A, OC1B and OC1C using timer in CTC mode
The timer module allows you to generate multiple outputs with different duty cycles, but they all will have the same fundamental frequency.  If you want to generate different frequencies, you will need to use a different method.  There are two main ways to do this.  First method is to use three timers, each operating at a different frequency.  If you are trying to generate relatively low frequency outputs (1 kHz or less) then you can use a reasonable timer tick and an interrupt routine.  If you want to generate 1 Hz, 2 Hz, and 4 Hz, you can set a timer tick of at least 8 Hz and then count ticks and turn the pins on and off at the right time.  With an 8 Hz timer tick, generating a 4 Hz output would require toggling the pin on every cycle, 2 Hz would be every other cycle, and 1 Hz would be every 4 cycles.  I would suggest using a slightly higher tick frequency - 1 kHz is pretty reasonable and it would give you the ability to generate a wide range of different frequencies.