Go to your projects by clicking on the dropdown next to your profile image and clicking "My projects"
You should now see all your draft and published projects. You can click the pencil icon in the top right corner of any project to begin editing.
Alternatively, if you click on the project title to view your project, you can click the Edit button under Project Settings in the Project admin panel at the top of your project page.
Once you are in the editor you can navigate through the sections of your project using the buttons on the top of the page. Don't forget to click "Save Changes" when you are done editing.