clear label item

Hi,

I have a listbox populated with items. When I click on an item, it is displayed on a label. Simple enough =)

Here's the fun part. I have added numberous items on to the label and I want to double click on a specific item to decrement it
( or if there is only one item, to clear it). Also, I would like to know how to make the quantity show if I click on the same item in the listbox.

Example:

Here is the list in listbox:
Pencil
Paper
Stapler
Eraser
Backpack

When I click on Pencil, it will display on label. When I click on Eraser, it will be on the next line in the same label. If I click on Eraser again, it will display quantity 2.

Pencil 1
Eraser 2

When I double click on the Eraser in the label, it will decrease it to 1 or if I double click on the Pencil, it will clear it.

Thanks a lot, your response will be greatly appreciated!! I am new to programming so please explain it as if I know minimal vb.