Now that you have the higher-level plot points written down, it's time to write your main character!
I like to use character worksheets to fill in my character profiles a bit more. I start with my main character, then branch out to cover all the main players: the MC's best friend, the love interest, the mentor, and the villain.
My Writing Process Day #2: Character Worksheets
I have sample worksheets similar to this one available for purchase for as little as $1.99! Contact me for character sheets and consulting to help you create your characters.