on the 877, it's pretty simple. RB.6 is clock (aka PGC), RB.7 is data (AKA PGD). on the PDIP 877, those are 39 and 40, respectively. you will have to identify the pins on your programmer's ICSP header. dont forget ground. If you need to power from the programmer (usually not recommended), hook up Vcc as well.
For low voltage programming, use RB.3 (PGM).
By the way, the datasheet calls this out pretty clearly on the pin diagrams. You probably just aren't familiar with the terminology.