ETS6 how to implement "if"logic?

Dear Sirs, 

please understand I'm a totally newbye coming from industrial automation, I'm trying to understand if I can implement this use case with ETS6:

if CURRENT_TEMPERATURE is less tha SETPOINT_TEMPERATURE and  PUMP status is ON then turn ON HEATER

I'v inserted in my project:

- ABB SA/S4.6.2.2 actuator 4 channels 6A: CHANNEL A: PUMP, CHANNEL B: HEATER

- ABB  AE/A2.1 analog input 2 channel: CURRENT_TEMPERATURE 

-ABB Bush-SmartTouch 7 

I've created a custom function copyng the heating continous:

0/1/5 Current Temperature: is linked to CURRENT_TEMPERATURE

0/1/6 SetpoinTemperature: what should I put here?

0/1/7 Operation mode HVAC

0/1/8 Window contact: I can see that Data Type can I be set as logical function, but how can I implement that logic?

Thanks in advance, BR