You have to load the bootloader with a PIC programmer first. The bootloader is
a small program that runs in your PIC at startup.
After the bootloader program is loaded into the PIC, you can use the bootloader from that point on.

If you are using MCLOADER, the appropriate file would be 16F876A_04.HEX or
16F876A_20.HEX, depending on what speed you are running your device.