The 6502 is LO HI, so you just flip the bytes so in RAM and in ROM you might have 34 c8 that is a pointer to $c834
Now the 10 might be $10 which is 16, which just happens to be the size of an iNES header, so if your ROM has a iNES header(stars with NES at the top of the file) then to get the FILE offset you would then ADD 10 to the address so $C834 will be at $C844 in the file. However the NES has banks so the PRG ROM is not linear as it is for say the GBA. FE 1 and 2 are MMC4 which can be found here https://wiki.nesdev.com/w/index.php/MMC4