If you are new to production management system and do not know what to do first start from inventory tracking. Production management means large area ranging from sales record tracking to factory inventory or cost tracking.
But it is true that in many factories production managemt starts from keeping track of the number of inventory. You can NOT forecast sales amount without knowing how many pieces of your factories' product A. Lots of software vendors in Bangkok Thailand repeats their software's advantage includes sales forecast and active inventory reduction. It is true that those software can provide hint for forecast and reduction but you must have inventory tracking data before doing anything.
Inventory tracking does not just mean tracking final product inventory but includes tracking of intermidiate product ( or a part) in your factory, which is called "work in progress" (=WIP). By knowing those number of inventory in a factory you are able to calculate cost (or value) of inventory in your factory.
Computer system (whether it is ERP software or tailor made production manaegment system) can store large amount of data and calculate the number of inventory and its cost easily. But you must have system, which is NOT computer system but is combination of rule and hardware to input the number of inventory to your computer system. These typically include scanning barcode of your product by manually or reading tag information attached to your conveyer.
Factories where the number of computer inventory and the one of real inventory does not match first need to make rule and start educating your employee before doing anything.