Instructions
Turn on your Nintendo DSi console and tap the "Settings" icon with your stylus or finger. The systems settings menu is represented by an image of a wrench.
Scroll to the third menu screen on the right and tap the "Internet" tab to access the Nintendo DSi Internet options.
Select the "Connection Settings" and tap the drop-down menu next to "Connection 1." From the drop-down menu, tap the "Search for an Access Point" option. The built-in Wi-Fi adapter will attempt to search for Wi-Fi connections. After the search, a list of wireless networks will appear as a pop-up message.
Find the Wi-Fi network that has a locked connection and tap the name from the list. A "secure" icon is represented by a locked padlock image.
Type the password of the locked wireless connection into the text field and press the "OK" button. The Nintendo DSi will attempt to make a connection with the wireless network. Once a connection has been established, the message "Connection Test Successful" will appear on the screen.