You take all your prepaid non refundable costs for your trip (excursion, air, hotel, ect) and add them together.  That is your total trip cost.  Trip costs are per person, if you are traveling with someone you add them as a traveler and do the same for them.  Typically events and excursions have very limited to no refund policies 90 days out and hotels or flights tend to have no refund policies once you are either a min of 24 hours before your departure or once traveling, where trip interruption coverage extends through the end of your trip.  Check directly with the traveler providers before to understand what is non refundable before and during your trip to come up with your total trip costs.