Start small. Solve one piece of the problem at a time. The project will grow over time.
For example, say you want to make a GUI app. The steps might be:
- Show an empty window
- Add some text
- Add a button
- Make the button do something
- Add another button
- Etc
For each step you might need to follow a guide or a tutorial.
Don’t worry if you do any step wrong. You can always make it right later. Nobody is designing the perfect software on the first go. It’s better to have something than nothing.
Don’t worry if you need tutorials, documentation or examples on the way. Everybody needs to use some reference. I recommend to start following a tutorial (e.g. how to make a GUI app), and use it as a starting point for the rest of the project. Go off track from the tutorial and explore on your own.