If you're using OpenSDA built in uart, you have to use B16 and B17 pins, in other modules you need to connect RX, TX, GND. Remember also to set properly baud and enable both receiver and transmitter.
If you want to use interrupts, you need to enable "on receiver full" interrupt methode and in the main file create ISR function like PE_ISR(yourISRnameHERE){...} or let PE do that for you (project->properties->PE->generate ISR).