I can't figure out how to add mods...

I just bought Terraria on gog (I really hate constant steam annoyances when I just want to play my game), and I can't figure out how to use the tmodloader to mod my game. I've hunted all over, found several videos (all out of date, apparently), but all are posted in 2016 and not a single one worked. I got two separate tmodloader programs from these forums (one from the generic page, and one from the gog specific pgae which didn't work), and one from github blushiemagic that was supposed to...

I can't figure out how to add mods...