Summer and Winter
A clean windshield is important all year long, but as long as you use real windshield washer fluid (come on, it's cheaper than bottled water!) you have a built-in anti-icing system, too. Washer fluid doesn't freeze, so if you spray it onto your windshield when you have some freezing problems, it helps to break down the frozen layer.
Fill It Up
It's a one-step deal. With your hood open and safely propped, look for the opaque white plastic bottle with the picture of the windshield and wipers on the cap, which is usually blue. Pop it open or unscrew it, and fill 'er up! You don't have to be scientific about it, putting too much in won't hurt anything. Done!