Frankfurt train connections
 

I am concerned, never having been out of the U.S., about finding the the place to purchase a ticket to our destination and finding the departure location. Could someone please give me detailed information?

You can buy your tickets at the train station. Tracks are numbered and you just go to the track your train leaves from. Where are you going to from Frankfurt? Which train station are you leaving from? The airport or downtown Frankfurt?

I think if you were to mention where you are arriving from, and where you desire to go. Whether you are planning to catch a train at the main station downtown FRA, or @ the airport..that then someone who is familiar with FRA can give you precise and details instructions and advise, as to where exactly to go, and what exactly to do.

In almost all major European cities the train station is a well known building.
Other than in Dublin, the main stations in every city I have visited are huge with many trains coming and going every hour during the day and early evening.
Public transportation systems are usually integrated with the train stations and almost every one in the tourist business knows where they are and how to get there.
Frankfurt has a large main train station in the city center and a large one at the airport. Trains from either one will take you to much of western Europe.
Ticket windows are easily found and most big city stations have agents who speak several languages.

First I will assume you can find the station.

Once entering the main entrance go to the left. But then you are arriving by train so ignore what I already said, instead get off the train and head towards the main entrance and the lines will be to the right.

People speak english pretty well in Germany so you should be able to tell the clerk what you want. Also, compared to other train stations I've been to in Europe (Italy) the lines are far less chaotic.

The ticket will state which landing to stand at, or, the ticket person can tell you if you ask.

As a last bit of advice, my hotel bought me a ticket (frankfurt to munich) which would be dispensed by a machine at the station. The machine had a german interface and was not easy to use at all. We required an attendant to help us. You may want to avoid making purchases ahead of time that require you to use such machines.