Is this the dress you are talking about? You have no instructions? Where did you get the pattern? Am I correct in my assumption that you are 13 and are sewing this by hand, in other words, not using a sewing machine?
If I were you, I would ask for help from someone who has experience sewing, and has a sewing machine they will let you use. I suppose that is what this post is about. There are so many things to ask, What kind of material are you using? If it is at all shiny, then you probably should consider the bias of the material, before cutting it. To late for that. I really would like to know where you got the pattern. You should use an actual dress pattern, and then modify it slightly to work. What are you using in the bottom to make the hoop stay out? There are numerous things that will work for that, You want to be able to remove it for cleaning purposes. All of these things need to be clarified, before I could help you at all.
Sorry, this doesn't help much.