You can create a private project. This limits the project to just you, and the users you invite.
To do so, click the + button on the left sidebar and type in your project name. Check the box for Make it private. Then click Create. If you want to invite your teammates and grant them access to this private project, click the share icon on the top right corner. Type in the person’s email address in the box and select what kind of access you want to grant this person. Finally, click the Invite button. You will see the project folder with the padlock icon which means it is private.