A project keeps everything together: the phases, the tasks, the files and the hours.
A project type
Start with a project type: the phases and the standard tasks every project of that type gets. When you then create a project, those tasks are already on the task board.
Create a project
Click New under Projects, choose the type and give the project a name. The project gets its own folder in Files and its own task board.
Logging hours
Open the Hours tab of a project and add a line: date, number of hours and what you did. At the bottom you see the total per project.
Reusing a template
If you have a folder with a handy structure, you can mark it as a template. A new project copies that folder and attaches its files to the standard tasks.