Welcome in the fascinating world of PSoCs!
You have two choices to change the state of a pin:
With Hardware. Then you have to connect a hardware signal from any module you put on the sheet to the input square of a pin.
By Software. Then you have at first to remove the hardware-connection by setting in the property dialog of the pin (double click on it) by unchecking the box "HW Connection"´. Now you may use "Pin_1_Write()" to change the pin's state.
You had wrote annotation parts on right side, those be with outside of PSoC.
Those just for notation, couldn't be for actual work.
On left side of the pin, you must connect some user module that you want to be.
Or delete the HW connection check box, and control by CPU(your program) as Bob said.
Hope you can be find PSoC enchantment soon.
Oh, thank you very much. I made it ! =)