We turn on the output bit (and light our LED) by using another function which is called in exactly the same way as our input function:

output_high_port_bit_a (0) ;

The complementary function output_low_port_bit_a will turn the bit off. Remember that these functions are particular to C2C. Other C compilers for the PICmicro will probably provide the same features but they may not have the same name.