K.V.
Check to see if your hospital has a Child LIfe Dept. Most children's hospitals do. They are trained child development professionals who can explain the procedure to your daughter in terms she can understand and relate to. They sometimes even have tours you can take before you have your surgery. This will help relieve a lot of anxiety about the unknown and will help you to feel better. As a teacher, I'm sure you know how children can sense what their parents are feeling and going through. Remember the things you know as a teacher! I am also an elementary school teacher but was a child life specialist previously. They have a lot in common.
One thing I did learn from my days in Child LIfe - no matter what! - when they tell you to begin giving her fluids after surgery -do it then and don't wait until the anesthesia completely wears off! The pain is more severe but similar to having a sore throat where it feels better once you are drinking and swallowing but hurts so much in the beginning that you don't want to swallow. If she starts swallowing while still under some effects of anesthesia then it won't hurt at bad and she will be more likely to keep drinking. This is important because the sooner she drinks the sooner she can get her IV out and go home!!!!
Also, ask about EMLA cream. It is a white numbing cream that can be put on prior to getting the IV and then there is less pain. Distraction can also help during the IV stage.
Totally up to you and I am not trying to tell you what to do - only relaying info. from prior experiences - use the correct terms and be honest with her if she asks questions. At 6 she needs to be able to trust and you don't want to jeopardize that. If you don't know an answer, tell her you need to ask versus making something up.
You'll be fine and so will she - honest. My son had this same surgery at just over 1 year - he didn't understand so that was hard. I do feel your anxiety though - as a mom it's never easy to see your baby go through anything painful.
Good Luck - I really think if you call CHild Life that will make a HUGE difference for you and her!