help with the pic16f877+c coding

hey there guys can someone please help me out. I am using the ccs ide and compiler to carry out a project. As part of the project i need to use Rb0 as as external interrupt. There is a sine wave connected to the pin. When the sine wave is positive the pin will be 1 and when negative the pin will be 0 due to the internal schnidt triggers.

Now what i want to know is everytime the pin changes from 1 to 0 or 0 to 1 i want to make a LEd conneted to on pin D_1 come on. How do i do this using c and the ccs environment.

Please please help