How do I create a production budget with two products of the same company? How do I get the fourth quarters desired ending inventory of finished units?

Too ambiguous.

You had to have either been given the desired ending inventory, or it is having you figure it out from information you've been given, like x% of next quarter's production needs, or something like that. There isn't any one given place to get this information from. You have to look and see what it says.

Having two products doesn't change anything. It's just done twice, once for each product. Assuming the production budget only needs to know how many units are needed to make, it's the estimated sales + desired ending inventory, - beginning inventory. (Finished Goods inventory.) For two products, you just do two separate ones, but listing both on your budget.