if you have a router that can broadcast Wireless B (this includes: B, G, and N; though you may have to adjust some settings). Just go into animal crossing into the WiFi connect section, open the settings (sorry, I don't own the game, so I can't give good directions on how to get there). From there you will see buttons that look like the DS startup interface, touch Nintendo WFC Connection settings (left blue button), ConnectionX "none' button, search for an Access Point (top wide button); or if you have an AOSS compatible router (not likely), touch AOSS insead of "search..." and press the button on the router. For further deatails, go to
www.nintendowifi.com