Open your "YourProject.cydwr" file - [Pins] TAB, You look the pins list on right side, Select the pin which you want to assign. Port columun can pull down, Choose Port and Pin number. That's All. OK?
As a general rule: Any physical pin can be assigned to a pin on your schematic. Some of the pins have dedicated functions and when you want to use them you'll have to use them for their purpose. This applies to VDACs, IDACs, amplifiers and other analog usermodules. Recently Chris Kees wrote an addition to Creator to name a pin and assign a physical port and pin number according to its name. Look here http://www.cypress.com/?app=forum&rID=79330
It is one of the confusing terms that people encounter when they used to work on other uC. It takes awhile to get used to.'
The port on PSoC can be used in a way of "PORTS" of our uC. you can read/write as a port. you don't need to wire it in the creator schematic.
But the best part of PSoC is that you can forget completely about ports and consider using pins. You can group pins (no need to be next to each other) to be output from a control register component. or you can group pins to the input as status register. and the register doesn't need to be 8 bit wide. you can use one or multiple pins to input or ouputs of logica gates and FF and nearly every pin can be digital/analog/input/ouput/bidirectional.