What to do at an airport?

In a few weeks I will be traveling internationally, but I've never flown before & to be honest I don't know the whole airport procedure? & Is it highly likely for someone to steal my luggage if I have it tagged with different colors? I

I don't know the whole airport procedure.
SO WHAT. You are not required to be a know it all.
You are not the First First time flyer to use the Airport.
Many at the Airport to help you find your way.
As it is your FIRST time go EARLY. It takes you a little longer to find your way from step to step.
As it is an International Flight at least 4 hours before departure. Should allow you some time to relax after you do the necessary stuff.
You check in. Go past security Go to your plane. That is it.
That you wander and look in shops, get something to eat use the toilet talk on your phone or whatever is the extra stuff.
Airport comes equipped with SIGNS, MAPS and Flight Departure displays to help you find you way. They all use this back up system called HUMANS. You can ask one for help. Many UNIFORMED staff to assist you.

Unless you have checked in online before leaving for the airport, you need to go to the check in desk of your airline when you arrive at the airport. If you have already checked in, then find the baggage drop off counter for your airline. If you check in at the airport, they will take the luggage you are checking in.
If they know the departure gate, they will tell you. If not, there will be screens showing where it is as soon as it is known.

Once through check in, go to security to pass through to air side.
When you are at air side, check the boards regularly while you shop or sit down. Once the flight is ready, the departure gate will appear on the boards. Make your way there and at some point, the boarding will begin. When you arrive at the other end, follow the signs to baggage claim. Each flight will be on a different revolving belt and most often, you arrive before your luggage does so you can collect it as soon as it appears.
It is unlikely that someone will steal your luggage.

Airports are well signposted, but if you get confused or lost, there's always a member of staff around for you to ask.

At the end of an international flight, you bag is protected well because only people from flights can get into the baggage pick up area and you then get in line to go through customs. Most baggage theft happens outside the airport when somebody offers to help you with your luggage.

I don't know what airport blackgrumpycat is describing. In most airports in the US, your departure gate will be printed on your boarding pass. You turn your luggage over to the airline employees and it goes on a conveyor belt, and gets loaded on the plane. My airline now texts me when my luggage is loaded on the plane, but you need to have the airline app on your phone. Then you go through security, and follow the signs to your gate.
In major airports in other countries, when you enter the airport, you have to look at the big screens for your flight number, and the screen will tell you the number of the check in desk. It will only open 2-3 hours before the flight. Go to that number, and check your luggage. Then security and out to the gate. I don't know of any airport where you don't know your gate number before you go through security.

No liquids in your carry-on. No lighters in your carry-on or your pockets. At security, take off your shoes, pull your laptop/tablet and put it in a bin by itself, empty your pockets, take off your belt and remove your coat/jacket. Have your ID and boarding pass ready when you approach the first station where they check them.
At check-in, you need your passport ready. You'll also need it when boarding at the gate. You're generally allowed two bags checked for free on international flights, but this has a lot of variation so you need to research this. If not, it's usually $25 to check a bag. Don't check more than one, because the fee goes up a lot after one.
You're only allowed one carry-on bag (a smaller rolling bag) and one "personal item" (purse, backpack, laptop bag) for the plane.
You need to show up at least two hours before your departure time. Probably earlier. It depends on the airport. Many airlines shut down check-in for international flights an hour or more before departure, so you need to be early in case there's a big line.
Upon arrival, you'll need your passport. Be honest with the immigration people. Don't write any declarations on your customs form (same goes for returning to the US) and go to the "Nothing to Declare" side when leaving.
When you return to the US, you'll have to pick up all of your checked luggage before clearing customs regardless of whether or not you have a connecting flight. If you have a connecting flight, you'll drop off your luggage with an airline staff member after clearing customs and it'll be checked through to your final destination.
If you're coming back from Dublin, Toronto and a few other places around the world (Google "us immigration pre-clearance" for the list), you actually clear US immigration and customs there instead of in the US. Otherwise, you clear when you come back.
Any questions, DO NOT hesitate to ask airport or airline employees. Don't just guess or follow people who seem like they know what they're doing.

Once you hand over your checked luggage, it goes yo a secure area ready for loading on the aircraft. You don't really need to understand procedures, just follow signs to departures after checking in go through security and if you know your gate number from your boarding pass, you can head there in good time for the boarding process, usually a time is on e boarding pass too.

Different countries have slightly different arrival processes, so it will probably be different to his you have previously experienced it. In the UK, you pass through passport/immigration then collect you luggage and head to custom.