Now that you've discovered the plot it's time to probe even deeper into character's mind and soul. To find out how he breathes and what makes him tick. I've tried numerous techniques of getting to know my character, and the one that is most helpful is mind mapping!
Obviously, start with the biography. Who he is, how old is he? What are his traits? What's his family like? Does he have one at all? Why is he acting in life the way he does? Why he does the things that he does, whether they're good or bad? Don't make your character too perfect because it will seem artificial to the reader.
Where is he now? Don't be afraid to tell the WHAT IS story at this point. Let's be real; s**t happens but that makes us stronger. And so it also makes our characters more stronger and human. IF you don't feel good with writing a tragedy, think of something smaller. Think of your current unpleasant situation and twist it in a direction that pleases you. Add some, detract some.
Where does he want to be? He must have a goal that's ultimately achievable, although a little/very tricky to get. You don't need to know who or what is involved in this (although it could help you if you knew), only the general knowing that your character will achieve his goal in the end.
What's stopping him? Now you decide on all the pretty details that are causing problems to your character. Let your imagination go as wild as you want to, as long as you keep the final destination in mind. Don't include any additional character that actually doesn't serve the plot because that will confuse the reader.
How's he dealing with it? This is an opportunity to show how well your character works under pressure or circumstances that make him feel down or troubling in some way. Don't be too emotional, but also don't tend to make your character look like a rock because even a rock can break if you hit it hard enough.
Does he get it in the end? Did he achieve his goal at last? Or was it just a partial satisfaction? Any way you choose is fine as long as you're happy with it and as long as you remind yourself that you must be the person who will enjoy the piece you wrote. Why? Because there will always be people who like what you wrote and those who don't like. So either way you turn, do it for yourself and focus on those who love it.