In the project tab you see a list of all projects. Each project contains its own commands, images and segments. Thus all work you do is within the scope of a project.
There is always at least one project, but you could make more. If you like to generate images about various subjects, or with various purposes, you keep things organized by defining a project for each subject or purpose.
With the buttons New, Copy, Merge and Delete you organize your projects.
At the right side of the page you see a whole lot of properties. The name of the project and a field where you can write notes, things you need to remember about this project or so.
All other fields below are defaults. Each time you create a command you specify a whole bunch of parameters. A new command will be filled with these defaults. Thus by setting them to your liking, you save yourself work.
A default prompt can come in handy when e.g. you want to try multiple commands with a similar prompt. Put it as default, and you only have to edit the differences.
On the page New you can define a new command. There we will look closer at these parameters.