dyzMerchant1. If you are installing it for the first time it is the same as normal. I made sure to unplug my other HDD though just to make sure it used the right drive. Otherwise I'm not sure how you might move it.
So I should just install it on there with the HDD unplugged then plug the HDD in after im done installing OS?
Not necessarily. During the windows setup it shows you which drives are available and you'll have to choose the one you'd like to install it to. Granted, you have options to remove or format entire partitions, but if you pay a little attention it's actually pretty difficult to do something wrong.
I guess it's not your first time installing windows? If not, there is nothing to fear. :)
EDIT: Even if it's your first time, just follow the instructions and you're fine.