sjbannat,

Welcome to the MOST friendly stamp collecting forum on the WWW, JMO.
I'm sure you Dad created a great collection and thus what you have received is something to be treasured. What country was your Dad collecting? Like Puzzler indicted, there is probably a stamp catalog of the country(s) in the collection. That, along with the collection in front of you is the best place to start. Learn what you have in the collection. I'm sure you'll find some surprises. Be advised that even if a stamp is old doesn't mean that it has a high value. Remember, most of the stamps were printed in the millions. Learn to use the catalog.If you need help, just post the question and I'm sure you'll get your answer and more.
It may seem overwhelming to start with but its fairly easy to pick up and learn about collecting stamps.
Good luck with your new collection/hobby and again, welcome to the family.
Art