Add to your oxinventory items and paste the images within the web/imgs

["note"] = {
		label = "Written note",
		weight = 20,
		stack = false,
		close = true,
		description = "A written note",
		client = {
			image = "note.png",
		}
	},
	["notepad"] = {
		label = "Notepad",
		weight = 2000,
		stack = false,
		decay = true,
		close = true,
		description = "A notepad",
		client = {
			image = "notepad.png",
		}
	},

make sure to add the note and notepad to a shop