I've read a lot of articles and watched videos, it is still not clear to me. Kindly provide some simple instructions and steps that I can directly follow.
There is a couple of ways you can do this!
The easiest way, if you don't want to manually partition your drives at install, is to remove the folders Downloads, Pictures, Videos etc. from /home and make new ones on your HDD and copy them as links to your /home directory (copy as links shows up when you right click on the folders), after that you have to manually drag the folders to the sidebar in files app if you want them to be shown there, if you do it like this your system files (hidden files) will still be on the SSD and everything you save will be on the HDD.
The caveat with this method is that you will lose your configs and so on if your system fatally crashes for some reason!