Rick,
you will need to re-pressurise the heating system via the fill-loop which should be positioned near to the boiler,you will recognise this as it has a chrome braided pipe with taps/valves at each end, you will need to open both and keep an eye on the pressure guage untill it reches 1.5bar(do not let it rise more than this as damage may result)
Paul, October 2008