How should I start a portfolio for a Fashion Design college?

How should I start a portfolio for a Fashion Design college?

Im a sophmore in highschool, I was origanally going to be an artist, but once I hit middle school I got fashion fever. I sew well, and I consider myself origanal.

What are the steps I need to take to plan a portfolio? How many designs should I have ready to show? How many design boards should I have? Should I make an actual outfit/dress to bring in and show, or wear?

Thanks in advanced!