how can i fix my ariston euro combi boiler?

I have just moved into a new home fitted with the boiler above, i have experienced problems the previous owner did not leave a manual.

I seem to be losing pressure very quickly, which results me topping up every day or the boiler doesnt come on, i'm also worried that alot of water is dripping from the pipe underneath the boiler although i have tightened the valve, there is also alot of water dripping outside of the house from the pipe connected to the boiler

please help me i know nothing about boilers!!!