Windows Server isn't really set up for web-based administration. Instead, you can connect to it via RDP, the Remote Desktop Protocol. This allows you to log into your Windows server and have it look and feel as though you had plugged an actual keyboard and mouse into the physical machine.
You can access your Windows server via RDP from devices running virtually any operating system:
If your workstation runs Linux, the command is rdesktop.
If your workstation runs Windows, the command is mstsc. A shortcut to this program usually can be found via Start -> Programs -> Accessories -> Remote Desktop Connection.
If you use a Mac, I recommend a program called CoRD because it is much more flexible than Microsoft's official Remote Desktop client for the Mac.
If you want to administer your server from an iPhone, iPad, iPod Touch, or Android device numerous RDP clients are available for those as well. My favorite is Wyse PocketCloud.
Note that, before you can connect via RDP, you should log into your Windows Server machine locally and ensure the following:
- Remote Desktop is turned on.
- If Windows Firewall is turned on, inbound Remote Desktop (port 3389) connections must be allowed.
- Your user account must have permission to access the computer remotely. This is most easily configured by going to Control Panel -> System, clicking the Remote tab, ensuring that "Allow users to connect remotely..." is checked, clicking "Select Remote Users", and adding your account to the list.