To add a user to SharePoint:
- At the top right-hand corner, click on the tool icon, and select "Site settings".
- Under the "Users and Permissions" section, select "Site permissions".
- On the top left, click on "Grant permissions".
- Begin typing the user's email address. When the list of options appear, hover the mouse above each option, and select the one that includes "EmailAddress":
- Click "Share".
NOTE for clients migrating from SharePoint 2010
Sharepoint 2013 uses claims-based authentication instead of Windows authentication (in SharePoint 2010). This means that all permissions assigned in 2010 are not applicable to 2013, and must be re-configured in 2013 by the organisation's site administrator.