first of all you need a 2.5" bracket to install it not a 3.5", if your case is modern, it should have, if not it's very cheap to buy, you just use a screw driver to screw into the bracket and slide the bracket into the partition, connect the ssd to your mobo, once you open up, mash delete to enter bios and make sure that drive is not on top of boot priorities, once done and booted into windows, enter control panel and search for manage hard disk partitions, you'll open a program called disk manager, you'll find your SSD with unallocated space, create a new drive using this space, and you're done, you can move files over, however if you want to install windows on that SSD, which I would recommend, backup everything you need and do a fresh install of Windows.