Hi, Ofir
From hardware perspective, you have to connect the external signal to TPM_CHx pin, all the TPM function share the same interrupt vector, so you have to check the interrupt source in the FTM0_IRQHandler(), which is the ISR of the FTM capture interrupt.
From software perspective, all TPM pins are multiplexed with the GPIO pins, this is the process:
1)enable PORT clock in the SIM_SCGC5
2)set the MUX bits of PORTx_PCRy so that the pin function as TPM.
3)configure the TPM module
4)enable interrupt for example
I attach an example for capture function based on KE02, pls refer to it.
Hope it can help you
BR
Xiangjun Rong