There are two ways to add a user, you can enter a new user from the administration menu/user management/users/add user, or you can activate a request from a user.
Navigating through the administration menu/user management/users/add user takes you to .../admin/user/user/create. Here you can create a user and password and assign roles for a new user. A user must be active and must have roles assigned to them to allow them to make changes to the site. Privileges around the site are divided between site administrator, editor, bio editor, and authenticated user. Other roles can not make any changes, though they can add comments (for that matter anonymous users can add comments). Save the setting for the new user. As an admin you can also edit any user's roles and password at any time. Of course you can use this method to create other editor users who are helping to edit or add articles to the site. See Using the Workflow in the help menu to learn more about setting up authenticated users to create node content.
Currently the site has a button on the home page that anonymous users can click on to send a request to become a user. We will likely want to remove that link once all the bio users are created or even sooner. Let me know. While that button is available, user requests will generate an email and send it to the site administrator (which is currently Matthew Schlanger, and later should be changed to Sherry Miller). The email will tell the site admin of the request, and give them a link to navigate to the user's request/status page. Click on the link while a browser on your computer is open, and you will be navigated to the settings page for the user requesting access. All you need to do is set the user to active and also you must set their role. They already created their password and entered their email. This is also a way to collect email addresses. The role options are bio user for people who can edit their own bio, an authenticated user who can create and submit new content, and, possibly editor if you want someone who can edit the site, like yourself. Bio users can edit bios which have an authored by name that is the same name as the user.
When creating bio users, after you create the user, copy the user's user name into the clipboard and then find the user's bio page. Edit the bio page and then change the bio's author to be the user's name by pasting the clipboard into the Authored by field. Once you do that the user will be eble to both log in and then edit their own bio.