Click the Steam button in the top left of the windows, select Downloads and then Steam Library Folders.
This will pull up an interface with your games and some info, press the plus and select Local Drive (D.
Once you have done this, click the box next to the game you wish to move and hit the Move button, make sure you're moving to the (D drive, this should be the only option.
This will take some time, but it is virtually harmless, so if you decide that the performance on your HDD is not to your liking, you can swap it back on to your SSD at any time using the exact same process.
This will pull up an interface with your games and some info, press the plus and select Local Drive (D.
Once you have done this, click the box next to the game you wish to move and hit the Move button, make sure you're moving to the (D drive, this should be the only option.
This will take some time, but it is virtually harmless, so if you decide that the performance on your HDD is not to your liking, you can swap it back on to your SSD at any time using the exact same process.