如何在Sublime Text（Gems）上使用Ruby on Rails

I know how to create new projects with ruby, and I've seen videos of people using it, but then I see them open a text editor with the name of their project (the one that they created with rails) and the Gems. Can someone help me understand this and how to use it? I am trying to create a simple login/logout/ and register pageI know how to create new projects with ruby, an