I am not going to give a detailed outline of the book, but rather a very broad overview of Romans.
The main theme of the book is righteousness. The book starts out with a very strong overview of the need of individuals for righteousness and our extreme shortcoming in that area. Then it progresses to the victory we have because God has provided our needed righteousness for us. Finally, he ends with how this new righteous standing impacts our lives together in the community of believers.
Basically, I divide the book into 3 sections: Deliverance, Victory and Community.
In chapters 1 - 5, Paul shows that all of us, Jew and Gentile, need righteousness but stand guilty before the throne of God. However, God demonstrates his great love for us by providing his son, Jesus, to be righteousness for us.
In chapters 6 - 8, Paul discusses the victory we have in Christ and how we are to live in this new righteousness. This is an area that has caused no small amount of confusion for centuries among believers. Paul shows us the difference between relating to God through the Law and relating to him through the spirit.
In chapters 9 - 11, Paul looks back through history to answer the question about whether God has been fair.
Finally in chapters 12 - 16, Paul discusses how we are to relate to each other because of our new righteous standing before God.
I think you will find this book a fascinating study. Some parts of it are difficult to understand. Some parts are easy to understand but not necessarily pleasant. However, the book as a whole is very pleasant for believers and I think you will find it a great comfort in your walk with God.