Sorry for sounding stupid but what exactly is included if you buy a Ryanair flight without any extras-I'm booking a surprise trip from Ireland to Liverpool for my family for 3 nights but as I've never booked any sort of holiday before I've no idea how the flight side of things works and I can't ask anyone as then it would spoil the surprise! 
Any help would be gratefully appreciated so that I know what I need to book! 😅