If you run a software update, everything in your box is updated. Select an offline update and have the box reboot after it's finished.
If the webinterface is installed, it must be listed under menu, plugins (it's called OpenWebif). If it isn't, install it, if it is, press "Ok" on it and it's setup opens. Check if it's enabled (first item should be "yes") and if the HTTP port is set to 00080.