how can i repressurise my baxi combi instant 80 he?

I've bled the radiators this evening and the pressure in the boiler has gone down to 0 and its making funny noises?? The fault light is flashing to indicate low pressure and I'm sure its down to me bleeding the radiators and not realising about the pressure but I'm not sure how I get the pressure back up?? There are lots of pipes and taps below the boiler but cant find anywhere in the manual what I should do??