The web interface of a VoIP phone is usually the best way to setup and configure your phone. It provides a control panel-style interface that allows you to enter your Gradwell account settings into your VoIP phone using your web browser.
To use it you will usually navigate to an IP address or URL provided in the instruction manual for the phone - please refer to this for information on how to access the web interface on your specific device.
However, because it provides full access to your account settings it is important to password protect the interface. This is especially important if you place the phone on a public IP address. Public IP addresses are accessible from any computer, and you could unwittingly be making your Gradwell account information publicly accessible.
Some devices ship with a default web interface username and password, however as these are usually "public knowledge" (because they are often printed in the instruction manual) we always recommend that you change it.
For the exact steps on how to do this, please see the instruction manual that came with your device.