All user management is done in Dashboard under User on the left hand site menu bar. Clicking on User setting you can go forward to user admin panel and firstly you have only one user that may be you and administrator of the account. Now you can invite new user as a community by clicking Add New User.
Now you see different options and role for the New User. Chose the Username, Email and other fields like Name, Last name, Website and Password. Here Password must be strong to prevent your own website from being hacked. You can also send password to the new user's email address.
Contributor is who can manage and writing the Post and publish them.
By using WordPress users community you can able to produce more content at the same time and have more current and updated site. With the firm handle in different users roles you can create a solid publishing network with lots of new contents.