locating & changing differential fluids?

[DerekSnowfall]

i want to replace my differential fluids and i dont know much about them.
online i learned its between my drive shaft and transfer case.
then i found out by somebody that transfer cases contain fluid. is that the front wheel drive? i havent even looked for it because its dark but im preparing for the worst. i just know to look for a drain plug but unsure where i can find it.also heard of having metal shavings inside ...how? thank you in advance