A parallel resistor would be in parallel with the crystal. I don't think that it is needed with a 16F877A, because that processor contains a resistor, shown in figure 6-2 of the data sheet. (
https://ww1.microchip.com/downloads/en/DeviceDoc/39582C.pdf)
what is the value of parallel resistor ?
The two oscillator pins, T1OSI and T1OSO, are input and output of an inverter. For low frequency crystals, 10 MHz and less, it can be a good idea to put a resistor in series with the output pin.
what is the value of series resistor ?
At 20 MHz it's not needed.
Your four capacitor pins are in a row. If you number from one end, 1, 2, 3, 4, you have pins 2 and 3 as ground. I was suggesting having pins 1 and 4 as ground and 2 and 3 as the ones connected to the crystal.