Of course, the same thing won't work for everyone, but here's what I did.
Assuming you encountered the same error report as me (which i will put below).
Once you have successfully installed the new Terraria_v1.3.2.1 (which is done by simply following the README's instructions, and it should have a jungle tree icon instead of a forest tree icon), put all of your tModLoader files in C:\Users\Family\Downloads\game\Steam\steamapps\common\Terraria, or wherever your "steamapps" folder is. Keep in mind that you may have multiple steamapps folders in different places, but if you follow this path you should find it. After doing this, you should probably make a new folder called 'Vanilla' and put your original vanilla Terraria.exe in there (I'm not entirely sure what would happen otherwise).
As long as the tModLoader files are in the Terraria folder at the end of the path described above, it should launch properly.