Time stamp, macro help!!

Currently need to come up with some code to make a 2 separate time stamps in my workbook. I have 3 columns, a:c and about 2000 rows. C is where my quantities for individual items are. I need to make a time stamp for whenever the quantity increases and another one for when the quantity decreases. As I said i have an item, the location and a quantity in columns with about 2000 items. Bed some help. Running 03' as haven't made any macros yet.

Please see attached

that is perfect. how to i implement this into my workbook? i am not a very excel savy person. i know my way around and can follow directions just fine. creating my own unless its a function i can type in , its a little difficult for me. i need to have it show up on sheet 2. right now i have A:C from Sheet1 copying into sheet2 when ever anything is added to sheet1.