That is to have an extended partition. Someone mentioned it to me today. That is some work of using Gparted.
The PC has 3G ram. It already has a swap partition from previous Linux installation. I assume it can be used for Zorin as well. I don't quite follow your first sentence. How can I use the "unusable" for /home?
In gparted, during install, you will have the windows partition, which hopefully you already resized and isn't the entire drive... you're first bootable partition. The rear of the space has to be separately partitioned, another bootable for the root ( / ). All your bootable partitions are configured. The existing swap partition can be mounted on /swap, and the remaining space can be formatted and mounted as /home. The only part of a drive that is usually unusable is the beginning, containing the boot records and partitioning table. You can remove the old swap partition (delete it) and add that to what you'll use for your home partition. That's a decision you have to make.
You could also delete all but the windows partition and create one big root partition and it will house everything (home, swap and root). If you ever reinstall a different or newer distro you lose all your customizations. That's why people use separate home partitions.
I hope that clears things up. Without knowing how many physical drives, sizes of the drives and current partitions, there really isn't anything more specific to tell you. Partitioning is also a design choice for your system, something you need to choose.
Thanks for your information. That, however, is too complicated for me. I just want to learn how to make the unusable dish space for the /home. The screenshot shows the entire hard drive situation: one drive with 120 GB. I don't want to touch the existing Windows installation at all. It isn't easy to get new Windows XP working properly nowadays. I have to deal with service packages and drivers. Too time-consuming.
The followings are two screenshots, one of an output of "fdisk -l" and Gparted.
Hope they can provide more current hard drive information.
Several suggestions here ubuntu install unusable partition at DuckDuckGo - maybe one of them helps.
If it was me... I would remove the swap. Installing zorin often will automatically create a swap file. Otherwise, creating or modifying a swap is very easy- about two or maybe three lines in a terminal.
Are you installing Zorin alongside of MX Linux? If not, I would delete the partition with the (-) button. Expand it into the unallocated space to make that one larger partition instead of two smaller ones.
I have resolved this issue by using Gparted coming with the Zorin Live OS. After creating logic partition under an extended partition, I am able to meet the Zorin installation guide with three partitions: "/", swap, and "/home"