Clone this to your Tree of Savior directory. When the game loads, you should see a message on every fps update.
You can edit data/addon_d/helloaddon/helloaddon.lua and reload it while in game. Open the developer console and use this command to reload it:
dofile("../data/addon_d/helloaddon/helloaddon.lua");
When you're ready to package it up as a standalone ipf, package the following together:
data/addon_d/helloaddon/helloaddon.lua
helloaddon/addon_d.ipf/helloaddon/helloaddon.xml
These two files should go in the same ipf and the structure should look the same as it does in the helloaddon folder.