D-Link DIR-890L User Manual page 22

Section 3 - Configuration
In order to secure the router, enter a new Admin Password. You will be
prompted for this password every time you want to use the router's web
configuration utility.
Click Next to continue.
The Summary window will display your settings. Click Back if you find it
necessary to make changes. When the settings are correct, make a note
of the of them so you can configure your Wi-Fi devices.
Click Next to continue.
D-Link DIR-890L User Manual 17