It may be difficult to pull off as a beginner and might be a better option for premier support.
The steps are:
1) Add a column to the products table for the inventory in stock and the date the inventory was confirmed
2) Save the orders in the database when running the eCart checkout wizard
3) Subtract any sold since the date confirmed from the number in stock when displaying the catalog
4) Add code to the shopping cart page that confirms the inventory and prevents users from adding more than the number in stock to the cart
