I'm going to go ahead and assume that when you talk about 4.9 you mean Micros 3700, RES 4.9.
The first thing you really have to know is that this system was not intended for Retail; all of the inventory features are based around the idea of ingredients. It allows you to assign ingredients to menu items, and then to use a count sheet to compute Theoretical usage, which you then compare to what you actually used. This feature if mainly available so that you can look for any major discrepancies.
That being said, you could of course adapt it for retail inventory. When you go to manager procedures and look at your count sheet, it will show you Beginning Amount, Deliveries for that period, Waste (which, of course, shouldn't apply for retail like yours), Theoretical usage (again, in your situation, this should be exact because we aren't talking about food stuffs), and then you manually enter the ending inventory based on the count sheet you can print and then fill out. Every time you accept a delivery, you are supposed to end the period, because it does NOT add the deliveries together if you haven't incremented the period.
If this sounds like what you want, I can give you a general overview of how to set it up. Be forewarned though, if you are looking to use this as a means to prevent selling possibly sold out items, it DOESN'T work that way. If however you just want to use it to keep track of your inventory, it can do that once you get over the fact that it was clearly designed around food recipes.