Create a new object and give it a function

[yomidseven 238]

good morning,
I would like to ask if someone could explain to me how and where to put my hands to create a new object, hypothetically a potion that shows 10%.
when I left, I had to create a folder with the vnum of the item and insert a lua/python script, but now I can't find all the items in the fs in that folder even though they work.
could someone please tell me the path where to find them and if anything has changed? thanks, I just want to experiment a bit