If I am adding a second drive do I need to get windows on the drive? And if so how?
Kind of depends. To answer your question, you do not need an OS installed on every drive in your system. Just one - your primary boot drive.
However, your OS should be installed on your fastest drive. So if, for example, you were using a HDD and just now got an SSD, I would personally transfer it over to the SSD and change the boot priority. If this is the case, that will make a world of difference.
But how would I move my os to the other drive. Pretty sure they the same speed
There are plenty of articles and videos on the process, however, I've followed this one in the past.