So Things you will need are :
Notepad++ (Guess you have this)
http://www.exilemod.com/download-all-the-files/LootTableCompiler-1.0.3b.zip
Time :)

 To start you will first need to pick your mods what you want loot to spawn from example I use cup on my server so I would want.
CUP Units and CUP weapons class names so you need to type into google,  cup units class names or weapons and you might find a link like this.
http://www.exilemod.com/topic/14360-cup-weaponscup-unitscup-vehicles-class-names-and-trader-prices/  This has all the class names for weapons. Also so you will need to do this to any mod you are using so example If you are using RHS you will need to find the same class weapons/clothing
Once you have them you will go into the zip folder unpack the LootTableCompiler tool, then go into the folder and open the LootItemGroups.h with notpadd++.
 Now you can see there is categories for each item, so lets say we want to add cup pistols we find the class names from the google links, then copy and paste them under the pistol list and under the other item class names already in the list.
Then add a spawn chance next to them just don't make the chance above 50% I find 33% is good. So this is what the classes will look like in the list after adding them https://prnt.sc/fsh47a so you need.
To do this for all the vests/ammo etc it seems long I know but the only way to do it so once everything is added under the lists you can then save the file.
And inside the LootTableCompiler tool folder drag that file you saved into compileloottables.bat file and a run box will open. And then you will be left with https://prnt.sc/fsh5om the table and we can help add it to your server if you need help :)
Hope that explains it well enough and you don't need to put the @Modname next to the class name in the list ignore that :)