You're at the Pennsylvania Avenue gate. Walk the grounds, go in through the North Portico, and visit the state rooms and the West Wing. Each room hides something: find all 18 for the full set of stars.
Computer: ↑ ↓ (or W S) walk · ← → (or A D) turn · or click the on-screen arrows · drag the mouse to look around (optional) · E or Space examine · M map · Shift walk faster
Phone: hold ▲ ▼ to walk, ◀ ▶ to turn · gold button to examine · drag the screen to look around (optional)