Good luck! It looks like you're close to paydirt!

Ive been on here for years and get tons of reseed requests but I cant figure out how to reseed or upload new torrents to the site to share.
All the instructions and suggestions I've found on here are PC based..

The process to create a NEW torrent isn't substantially any different for a MAC than for PCs, except that you cannot use the "QTM" tool on this website - it's designed for one specific client on PC systems...

Not to fret, I don't use it either!

Let's start with this tutorial:

• First, you already use a Torrent Client... I use qBittorrent across multiple platforms (esp. Linux), but you probably use something else... either way, it's how you're downloading files now, and I'm not going to go into details about your client here... almost any Torrent Client program will do!
• So now, you already know how you download a .torrent from the GT.ru tracker, open the .torrent file in your Torrent Client program, and it proceeds to download your file(s) from the seeders (if there are any).
• You will use your same Torrent Client program to CREATE a .torrent file.
  A .torrent file contains information - including checksums - about the file (or files) in your torrent. That's it! It doesn't contain anything else, and whatever torrent client you're using, it'll have its own way of creating the "new" torrent. (It's usually in a File, Tools, or Utility drop-down menu in your client)
  One important step: you will need to identify the tracker you'll be using for your torrent: For us (GT.ru) its: http://tracker.gaytor.rent:2710/announce
• Once you have the .torrent file created, you'll need to upload it to the "tracker" (again, in this case, GT.ru). But that's not all... the .torrent file has all kinds of data about the file(s) in your torrent that are important for the computers, but not the kinds of data that OTHER PEOPLE would use to determine if they want to download it.
  In the Upload function of this site (Torrents drop-down -> Uploads -> Upload Page link (in yellow?), you'll select a Category for your torrent from the drop-down, and that will make a BUNCH of other options available.
  SPECIAL NOTE: This tracker's policy is that you must upload a PICTURE from your torrent - for me, this is usually me going to the site where the video originated from (e.g.: https://www.helixstudios.net), finding the video, and snagging a pic from there...
  Everything else you should be able to guess at and be pretty close... the title of the torrent is (by convention) the file name (or the folder name if multiple files)...
  At the end (bottom), you will upload your .torrent file - the one you created in your Torrent Client above...
  ... but you're still not done! This tracker keeps records, and wants to "stamp" your upload to differentiate it from anyone else's... so, once your .torrent and descriptions and photos are uploaded, the system is going to ALTER the .torrent file... which means you now have to DOWNLOAD your OWN TORRENT to get the right tracker information!
• Click the download link - and now here's the "trick" - you have to point your Torrent Client to the same location where your source file (or folder) are located! The client SHOULD recognize that the files are already there, and CHECK THEM against the torrent file...
  If the check passes, you will immediately start seeding (and your torrent becomes visible to others!)
  If the check does not pass, either you changed something having to do with your torrent (renamed a file, deleted one, etc.) or you didn't tell the Torrent Client the right place to find your file (it's not uncommon to accidentally choose a folder above or below the right one...)
• You can throw away the .torrent file you created initially

You also mentioned re-seeding... say there is a file you downloaded 6-months ago: abc.mkv, that has a great flick on it that you've kept... and then, lo-and-behold, someone asks for a re-seed. Here's how you do that:

• Use the re-seed request message itself to find the file on the tracker - it's likely dead now (unless others have already started re-seeding)... so the link is the best place to start
• Re-download the .torrent file from the tracker
• In your Torrent Client program, locate where you've stored the file (abc.mkv) so that the tracker - just like when you uploaded your own torrent - immediately sees that the file is already there! The Tracker Client will check that the files are still the same, and immediately start seeding.

I know it's not simple and straightforward, but it's also not THAT complicated!
If you need help with your Torrent Client, post back here which one you use and I'll try to help...