How would one even begin to book a trip to Greece, Italy and Paris ...

Look up the cities online and find the places where you want to go and the things that you want to see. I suppose that you come from the US and have never visited Europe or something like that, haven't you? :-) ... The agent can get you tickets, book the hotel, and get u the transportation u need once u get there. Another solution would be to go with a GROUP on a tour. These trips take u to all the “must see” places, and u get to meet new people if this interests you. ...