This is what the manual says
Connecting to the Wireless LAN
You can connect to the wireless network with HUMAX Wi-Fi USB Adapter (Optional accessory).
1. Insert the HUMAX Wi-Fi USB Adapter into a USB port.
2. Go to Menu > Settings > System > Internet Setting > Configure Wi-Fi.
If the Configure Wi-Fi menu is disabled, check that the Wi-Fi USB Adapter is inserted correctly.
3. Select the network name from the list of available wireless networks.
4. Select the Security Type of your wireless network. The default is WPA-PSK(TKIP).
5. Select Password and press the OK button. Enter the password and press the YELLOW button to
confirm. Select APPLY and press the OK button.
6. After the wireless network is connected, press the OK button.
Note: HUMAX Wi-Fi USB Adapter is supplied free with HDR-2000T/1TB/WD but available as optional accessory for other Humax models.
Do you have the wifi adapter? You’ll know if you can see the name of your wifi.
Has your wifi password been changed at anytime? If not it should be the one on the back/bottom of the router.
Is it definitely the wifi password that its asking for, or is it a password for the box? On the front of the manual I looked up it says the default password is 0000 (thats 4 number 0)