Most front desk software has the reservation system built in. I've been at this racket for over 30 years and yet to see one that doesn't.
So what you need to have is:
Date and time reservation placed
Taken by which person
Guest first name
Guest last name
Guest street address
Guest city
Guest state
Guest zipcode
Guest contact phone number
Guest alternate phone number
Type of room (1 bed or 2)
Smoking or non
Special requirements (handicapped?)
Arrival date and time
Departure date
Room rate tax included
Credit Card Number
Exp date.
Security code
Type of card
And I'm sure I've left something out. But that should get you started.
A database will be your best bet. Office can make a demo model but Opera is the cat's meow.