You will need to be properly broadcasting a signal in order to connect the Wii to the network. Refer to your router or modem's instructions in order to properly set up your network.  If you can connect to your network with other wireless devices, then you should have no issues connecting your Wii. No special adjustments need to be made to the wireless network to accommodate it. If you don't have a wireless router, you can attach the Nintendo USB Wi-Fi adapter to your computer to make a specialized access point. You will need to install the software that comes with the adapter onto your computer, and then plug the Nintendo USB Wi-Fi Adapter in. Use the Wii Remote to select the "Wii" button. This round button will be located in the bottom left of the Wii Channels screen. Click on the arrow on the right side of the screen to scroll to the next page of options. From the Internet options, select "Connection Settings." This will display three different connections. If you haven't set up any connections previously, they will all say “None” next to the Connection number. None." Pick "Wireless Connection" from the menu. Then click “Search for an Access Point.” The Wii will begin searching for active network connections. After detecting a network, a screen will open asking you to select your access point. Press OK to continue. You should see the name of your network appear along with the strength of the connection. If your network has a password, a box will open asking you to enter it. Enter the password and select OK.  If your access point does not show up on the list, be sure that your Wii is within range of the router, and that your network is configured correctly. You can manually change the type of encryption by clicking the orange encryption name (WEP, WPA, etc.) If you are using the Nintendo USB Wi-Fi Adapter, go to your computer at this point and accept the connection from the Wii using the installed software. If error code 51330 or 52130 pops up on your Wii, this means the password you entered for your...

TL;DR in Vietnamese:
Đảm bảo mạng được cài đặt chính xác. Bật Wii và nhấn nút A trên điều khiển Wii để truy cập menu chính của Wii. Chọn "Wii Settings" (Cài đặt Wii) và mở menu "Wii System Settings" (Cài đặt Hệ thống Wii). Chọn "Internet" trong phần System Settings (Cài đặt Hệ thống). Chọn "Connection 1: Chọn mạng. Lưu cài đặt. Kết thúc cài đặt.