I have already reserved seats and meals for us on the flight. All you need to do is give you passport and your attached flight reservation at the Thai check-in counter. They will give you a Boarding pass, your passport and a ticket if you check in any baggage. Also at the check in counter, you will need to take an Immigration form and fill it in. Next you proceed for security check and immigration (passport check). Go to immigration for Thai people. Have line for Thai people and farang. At Immigration, give your passport, filled immigration form and boarding pass. Immigration staff will stamp departure on your passport, staple your return immigration card and stamp your boarding pass. Make sure you get your passport and boarding pass back from the Immigration officer. After you pass immigration, it is the duty free area. Please check your boarding pass for your flight Gate number.