You mention the first line of code, so I'm assuming you're talking about software. If you're having trouble getting started, it could be because your idea is no

You mention the first line of code, so I'm assuming you're talking about software. If you're having trouble getting started, it could be because your idea is not clear enough in your mind. How can you get to where you want to go if you don't know where you're going? Creating a low fidelity mockup will help with this. You'll start to have a better understanding of how your product might be used, and then you'll start to see how the domain objects in your project relate to each other. You'll start to see the data requirements and you'll start to see where user actions take place and where API calls should be made. It will be easier to know what to do next if you can get to that point. That mockup can serve as a tool for communication. You'll be able to divide up work and assign it to people. Most of us that decide to be a part of something are just happy enough to be along for the ride. People want to and enjoy helping other people. You just have to let them know how they can.