Once you're set up as a Stencila account user decide whether you want to create a project under your personal account or under your organization. The advance of creating an organization is so that a collection of users can be associated with it and work collaboratively on projects.
Navigate to projects on the top header bar.
Choose the account which the project will be owned by.
Create a project name. All lower case and unique for your account. Note it will be used in the URLs. e.g. https://hub.stenci.la/awesome-org/great-project
Your project will automatically be public which means any Stencila users can view it. Click if you want your project to be private.
As the creator of the project you automatically become the project owner. This gives you full authority to make changes or delete the project.