ok, white sauce then cheese.
What is white sauce? milk and butter?
someone, just tell me like I am 4, I am such a stinkin literalist.
all I want is some mac and cheese 
Melt 2 tbsp. butter and add 2 tbsp. flour. Cook that for a little bit until it's nice and bubbly,then whisk in 1 c. warm milk. Cook over medium heat until it bubbles and thickens, stirring frequently. Take it off the heat and add grated cheese, probably a cup or two, and stir until it melts. Don't overheat the cheese or it will separate and get grainy. Add seasonings to taste--I usually use salt and white pepper, plus some mustard powder and maybe a bit of nutmeg. The mustard enhances the cheesy flavor.
Now add your cooked pasta, stir it around, and either eat it right away if you're impatient, or pour it into a dish and pop it in the oven at 350F or so for about 15-20 minutes.
When I'm making it, I usually top it with some breadcrumbs that have been sauteed in a bit of butter before I bake it. The crispy breadcrumbs are the best part, in my opinion!
If the sauce is too thick or thin for your taste, you can adjust the quantities. Just stick with equal parts of butter and flour.
chary beat me to it!
(Edited because I looked at my recipe and discovered it should have been 2 tbsp. butter and flour, not 1 1/2)
