Relocate iTunes library

This is simple as long as all your media are contained within the standard iTunes folder (which is the default). Assuming this to be the case:

• On your HDD, create a folder called iTunes in the root of the drive - i.e., if the HDD is drive D:, this will be D:\iTunes
• With iTunes not running, copy everything in the folder C:\Users\username\Music\iTunes to the folder just created on your HDD
• Hold down SHIFT as you start iTunes, when you see this prompt:
  
  click on Choose Library... then navigate and select the iTunes Library.itl file in the new iTunes folder on your HDD

Once you've checked that everything is present and correct, you can delete the C:\Users\username\Music\iTunes folder to free up space on your SSD.

Two other points:

• After moving the library, check the settings in Edit > Preferences > Advanced:
  
  1. This should point to the iTunes Media folder on your HDD. If it doesn't click the Reset button which should set it to the default (D:\iTunes\iTunes Media if your HDD is drive D:)
  2. Keeping this box checked allows iTunes to take care of folder and file naming within your library
  3. Checking this box ensures that all additions to your library, independent of the method used, and copied to the iTunes Media folders on your HDD.
• Once you've completed this process use an external drive to create and maintain a backup of your library - see turingtest2's user tip on Backup your iTunes for Windows library with SyncToy for a suitable/recommended method.