I have a particular program that I'm trying to install to my hdd instead of my SSD but it doesn't give me the option to change the directory. What do I need to do in order to install it to my hdd?
Some programs don't allow changing of the install directory. I know people can do a work around via hard-linking, which to be honest I know nothing about.
Do a custom install - in the advanced settings, it should allow you to choose where you want to install it.
Yeah, go slowly through the Windows that popup, it might not be obvious where the "choose custom install" option is. You might want to google "custom install for (programname)" as well.
It's possible to edit the registry as well to change the default install drive, which you might have too, it's not that hard, just google "Change default install drive in registry"