How can I get my '01 Audi TT windshield washers to work again?

I have found out that the washers on my Audi TT for the headlights work but not for the windshield. Is there a certain sequence I have to perform in order to switch between the two washers or am I just lacking washer fluid?|||you are quite possibly lacking washer fluid, only recently replaced mine, pop the bonnet and it should be on the left side, then again a warning light should have come on at some point to indicate that the fluid levels were low.