HELP!!

Hey im turning 16 next march and im having my party at my house we have a huge backyard about 2 acres with a pool and huge deck with tables my uncle had his wedding repectation in our backyard this summer so we are using some of the stuff from the wedding like a fountain for the pool and park of the deck is going to be used for a dance floor where going to have a dj and since we live in louisiana and the party is going to be end of feb beg of mar the pool is out of the question i want something dresses like semi formal wondering how to do this outside at this time of the yr also ideas about decatortions and my dress and colors to use would be great! thanks!!