Can't shrink volume / partition HD after Zorin8 core install for other distro
 

I installed Zorin 8 core on an older laptop, it was (is) a total install on its own, I installed ( over ) Vista. Then when I wanted to shrink the volume of the 320 gig hard drive and make several partitions for several more Ubuntu/Linux distro's, the GParded ( thingy ) won't let me shrink/partition the hard drive. That option is grayed out and not usable, what did I do wrong, and what is an easy way to fix it for 63 year old Linux/Ubuntu newbie. Thanks.

Probably mounted - best is to use a gparted liveCD; this runs from the CD/USB and has full access to the disk.
Here is the relevant page - either burn the iso to a CD (as an image), or click the link on that page to learn how to setup a USB.

gparted from zorin os dvd ?
 

So you mean that I can use the gparted within the zorin 8 dvd I used to actually install it on my hard drive. Just boot from the dvd and once up and going, go to gparted and create a partition on the hard drive that way ?

Yes, that should work. Keep in mind that partitioning is always a system critical procedure which can lead to data loss when failing, so make backups of your important data first, if you don't have already.

This is a new ( three days ago install ) so there is nothing to save, If I screw it up, I will just install the zorin 8 os all over again. Now, if I have to do that, is there a way at the beginning of the fresh install to partition the hard drive. Remember, newbie here...Thanks.

You'll probably get a screen that says something like "Installation Type" - which defaults to erasing the entire disk. There should be a "radio button" for "something else" or maybe "expert". Click that and proceed - then you can manually partition.
Make sure you assign filesystem(s) (at least / - the root) to any partition(s) created. Perhaps create a swap the same as at present (or re-use that one). Have a play around - hard to do any damage on a new system like that.

I think you should be able to do your partitioning as suggested above, using the Zorin install medium and GParted. You can modify partitions from an installed system containing GParted but not the partition it is running from. I'd try this first.

If you need to reinstall, you will likely see an "Install Alongside" option (since you already have an OS - Zorin, Erase disk and "Something Else". The last option is basically a manual install where you need to make a number of choices. In your situation, selelct the Erase and use entire disk.