Um, /home does not go under /usr. When you create your partitions, you’ll need at least a root partition (mounted as /) and a swap partition, and maybe ─ depending on your hardware ─ an EFI system partition (mounted at /boot/efi), if you don’t have one already. But you can reserve some room on the SSD for an extra partition, to be mounted at /home. If you don’t do that, then the contents of /home will be living on the root partition itself.
To a UNIX system, there are no drives. There is only a uniform directory tree. But some of those directories may have their contents physically residing on a separate storage medium, be it a separate partition, a partition on a separate (physical) drive, or a filesystem on a different machine in the network.
To the end-user, it’ll all look the same ─ /home is /home, and it’ll always sit in the same place of the root directory. But it is recommended to have the contents of /home on a separate partition, for reasons explained higher up.
When you install the system, you must create partitions either way. So if you create an extra partition for your data, then you simply tell the partitioning tool that it must be mounted as /home, and then the system will automatically mount that partition into the tree at boot time.
Likewise, if you’re going to use the HDD for backups as I recommend you would, then you should create a partition for this on the HDD. But if you’re going to use timeshift for backups, then you don’t have to tell the installer to mount the backup partition. When you set up timeshift, you simply tell it to use that HDD partition and it’ll automatically mount it ─ usually under /run somewhere.
Note 1: Do not use NTFS for either the root partition, the /home partition or the backup partition. UNIX filesystems store permissions and file ownership information in the inodes of the files. NTFS does not support this.
Note 2: It’s not /USR and /HOME, but /usr and /home. UNIX is case-sensitive. 