Navigating DC is simple after you learn how the streets are laid out and numbered. The streets were patterned after a grid system that makes figuring out where you are simple and easy.
The US Capitol is the center of it all, just think of it as 0. The street names and address numbers radiate out from the building. The further from the Capitol the higher the address number will be. Capitol street cuts the city into 4 quadrants. North West, North East, South West, and South East. Remembering these quadrants isn't as important as the next bit.