Transfering Data from one Form to another Form

Hello,
I’m new to access. I’m trying to create a data that inventories items. I have on form that has the item in master record (ie Kegs). When user selects item brings up another form that the user must type in buyers name. This counts the buyer. I want the first form to subtract the total of buyer from the second form. Thus creating an inventory of items in store. Can someone please help with this.

Kevin