Sorry, blue, I don't know the answer, but IME with DAB radios, there's normally an 'auto tune' button, which scans for available stations, after which you scroll through the list to select one. Usually you can also allocate a certain number of stations to pre-sets.
Failing that, the Hitachi site doesn't appear to offer downloads of instruction manuals, but there is a technical enquiry form:
http://www.hitachi.com/GlobalSupport/ContactUs ?form_type=global_support
Media & TV / Radio is really for discussion of radio programmes, and is a very 'quiet' part of AB - perhaps you'd have more success in
Technology / Electronics
Of course, all of the above is assuming that DAB is actually available in your area - UK coverage is not exactly 100%. Do your neighbours get it?