PIC 16f84 programming

I need to create a programme to do the following, I have tried writing this in C but no joy and am now extremley stuck!

The programme needs to:
Count down from 3 seconds

-Look for an input on RA0 - if logic level high then output on RB1 logic level high for 3 seconds, if not keep a constant output on RB2.

Any information would be greatly appreciated.

What have you tried? What didn't work?

If you would like some help with your C code, why not paste some so we can advise you what to do better.