Take a deep breath and read all the requirements.
If you need to create a new rails app from scratch, reference this: https://gist.github.com/ryanflach/9fe657471bc9282a18d6904171645278
Set up Heroku:
Start a pomodoro timer and get going with good git practices, create a new branch and plan on commiting often.
Start with a test. If there already is a test, fix it.