What to expect first time flying?

Im only 16 & Im planning on flying to Louisiana (by myself) to visit my dad. This is the first time I've ever flown so I am nervous about being alone because I've never even been in an airport so I have absolutely no idea what is coming to me. I am only taking one duffle bag of clothes and my purse so I don't know if my bag is small enough to be a carry-on or not. I was also wondering if it was possible for me to have an escort onto the plane to help me so I don't do anything wrong. I flying from Pittsburgh national Airport and then I have to stop in Houston Texas then board a smaller plane to Alexandria, LA. Can someone help me on how to handle all of this?