This is very hard work. it will require most of your free time. You need to study acting and practice with some small plays to get the feel of the part. Make sure you have a good photo shoot to show of your many moods. Then start trying out for the smaller parts in movies and if you are good enough you can make it to the top. Best of luck
First step is to join a casting website such as broadwaystar or broadwaycasting. They are not just broadway, but films too just to let u know. You can then get billons of offers for casting near you. The sites are great for new faces who want to get noticed. Just stay determined and keep at it untill you find a good opportunity. Meanwhile, score brownie points with the casting crew by gaining experience. Audition for lots of unpaid local plays and focus on improving to the best you can be. Break a leg, and hope to see you on broadway!