Automatic placing with configs

Ok so im making a little shop and I was wondering how In a config when players add a new item it lets say places a box in a position on the menu.
So each box is located 300, 100 (Im not using ScrW and H for this example) in the menu and if someone adds a new item in the config it will add a new box at 300, 300 in the menu.
So it moves it 200 down automatically every time theres a new item added?

Start with setting a local variable

local yxks = 100

Then each time you make a new item, plus the variable with 200

 yxks = yxks + 200

And then you just set the height by calling yxks.