Simple: But first, let's put you in God's shoes. Let's say you are a videogame developer, and you create a game. Let's say the people can breathe underwater and there is no gravity. Now, are you subject to those laws? Can you breath underwater or float around? Of course not, because the laws of the video game do not apply to you because YOU CREATED those laws. Now, let's go back to God. God does not have a creator, because he made time. Time has a beginning and an end, because God created time, he is not subject to it. Therefore, he was not "begun", meaning he doesn't have a creator. Hope that made since, I understand that it can be a bit confusing or weird to think about!