Lets Begin:

Unpack everything. Drives come defaulted to be ready to be installed in a single drive environment.

First of all Master, Slave? What is this? They had to be called something. I've seen some various organizations promoting some campaigns to rename this due to the slavery reference, but I don't see any harm. The master can also be referred to as the "primary" drive with the slave being the "secondary". A lot of people like to use what is called Cable Select. If you want to do that you'll just have to make sure that it's plugged into the right part of the cable.

Wonder what connects to where on the cable?

If you want to make it a slave or the master with a slave present you will have to look around the drive to find where the instructions are. You'll see some kind of diagram that looks like this:

It's not currently set, but you can fairly easily tell from the diagram what you'll need to set it for.

Before you install the new drive make sure you unplug the power connector from the computer. Anytime you mess with anything inside your computer it is a good idea to unplug it. It's also a good idea to touch the power supply before you go sticking your hands in there! Static discharge can jump and do some bad things. Just touch the power supply for a precaution OK?