me and my friend are trying to figure out the loot table but its not working.... how to sort this out? 

I recommend watching this tutorial https://www.youtube.com/watch?v=X7KxnfecX_w

we kinda did the same as him but is so diffrent from nitrado D: D: so idk what wrong we did

You only edit the data\BetterLoot\LootTables.json with the plugin unloaded or the server down, you edit/save/validate with json validator then reload the plugin/start server. data configs will not retain changes if the plugin is still running.
Mine is working with no problems.

Usually with large files i copy the file to a "new text file" and edit it , then unload the plugin after all checks have been made remove the default data file and replace it with the edited version/save then reload the plugin.  I do this mostly as my server host dashboard only allows a 5-10 minute connection before logging you out , this way i can relax and edit at leisure.