transmission rebuild

It is an auto but I am not sure that I am up to speed on how to do it myself. Same with the engine. I would love to do it myself but I would hate to get it apart and discover that I bit off more than I can chew. What skill level should I be sitting at to take this on? Luckily it's not a daily driver so it's not like I need it done quick. But I don't want it sitting out there for several months either.