Doing this will open a window with wireless networks around you.  You may first have to click ^ to view the Wi-Fi icon. If you see an "x" next to the Wi-Fi icon, click it, then click Wi-Fi Off to turn Wi-Fi back on. The network you're connected to will appear at the top of the pop-up window. You'll see "Connected" beneath its name. You'll see a list of network names in the pop-up window; each of these names is a specific network's SSID.

TL;DR in Vietnamese:
Nhấp vào. Tìm tên mạng hiện hành của bạn. Xem qua các SSID có sẵn khác.