Can't get PIC 16F876 working.What am I doing wrong?
With the bypass cap missing, nothing else matters.

I'd also move the LED off of RB6 or RB7 since those are the programming and debugging lines.  You won't be able to use either of those pins while debugging.  RB5 is a good choice.  I don't understand why you'd use a pin multiplexed with anything else when all you're trying to do is test that code is running by seeing a LED blink.

Tie the PGM pin (RB3) to ground.

Don't forget to clear the TRIS bit for the pin you are using.

Test the code in the simulator first.  There's no point trying it on hardware until the basic code is working correctly.