1. Prepare the mac'n cheese according to package directions.
2. Just before serving, (and while still hot) stir in the salsa.
3. *Note: Whenever I make this recipe adding salsa that's has more heat to it, (like my husbands homemade 'hot' salsa) I only add 4 tablespoons to the mac 'n cheese, but if I use a store bought brand that's not so hot, and is a medium-heat tasting salsa, then I'll add 5 tablespoons of the salsa.