I need to find a dress/shoes/accessories for my cousin's wedding? teen girl?

I'm 15 and my cousin is getting married in June. Its an afternoon wedding and I need a dress and shoes and jewelry. The wedding is an indoor afternoon wedding so I can wear pretty much anything so ya. I want a knee length or a a few inches shorter dress with any kind of sleeve/sleeveless and either small heels or flats. Any color/print as long it doesn't clash with red hair and brown eyes. Thx in advance!