I will be traveling to Erie PA in the USA for the 1st time and would like to know how do I check in my luggage and how are they transferred between flights. I will be flying through Delta airline from Johannesburg to Atlanta, Atlanta to Detroit then Erie.
When you get to the airport in Johannesburg, there will be check-in counters for Delta Airlines. Get in line there, and an airline agent will check you in for the flight, ensure you have boarding passes, tag your checked luggage, and take your checked bags to be put on the plane. At this time, you can confirm with the agent that your bags are tagged to be delivered to Erie, Pennsylvania (the airport code ERI should appear on the tag). You'll then be able to go through the security checkpoint and head to your gate.
After an exceedingly long flight (one of the longest non-stop flights in the world in fact), you will arrive in Atlanta. Here, you'll follow the hallway to the immigration hall (it will be the only way you can go, so you can't get lost). Go through US Immigration ("passport control"), and you'll find yourself in a baggage claim. Check the TV monitors to see which carousel is serving your flight, and make sure you pick up your checked luggage. This step is important and is one travelers sometimes miss. You'll take the bags through US Customs.
Then, there will be signs that say "transfer passengers" or "connecting flights" or something similar. Follow those signs and you'll reach a bag drop, where you give your checked luggage back to an airline representative. If you can't find it, there will be uniformed staff present you can ask. You'll then continue through an airport security checkpoint and be inside the Atlanta airport terminal. TV monitors will show you what gate to go to for your flight to Detroit, and there's a train between parts of the airport you may need to take.
In Detroit, there's no need to collect your luggage (assuming you've purchased one ticket for this entire trip). Just check the TV monitors to find the gate for your flight to Erie, head there, and board at the appropriate time. Signage should help you find your gate, and airport staff are available to help too.
When you arrive in Erie, follow the signs to "baggage claim" and collect your luggage. It's a fairly small airport.
If you have any questions along the way or aren't sure where to go, just ask the airport or airline staff and someone should be able to point you in the right direction.