-When you begin the story, the lights go out, and everyone appears shocked. Is it realistic to say they kept dancing, with the lights out, while they're pretty shaken up?
-Noone really seemed phased by the fact that he just randomly walked off into the trees. Wouldn't that seem sort of strange, if you were the one observing?
-The setting isn't described. The setting needs to be included, in order to create imagery, which is a very important part of storytelling.
-A "hot man" is not a good description. It might be appropriate in dialogue, but it is a very poor descriptive phrase.
-The flashback part is unclear. When you're beginning to write, it's important to add "* * *" when there are significant changes in the time period, until you are able to make it more obvious for the reader.
-"Now its three weeks later and just a day ago the police found my sisters dead body lying in a dumpster." is a terrible way to describe a turn of events. You should show, not tell what is happening (through action, rather than explaining).
You're quite talented! You're also very good at describing things. Keep writing!