SharePoint - How to Grant Access to a SharePoint Site
Access can be granted by on the site administrators for that SharePoint site. Please ask the site admin to add you. They will add you by clicking User Management under Tools as shown below:
User is trying to view documents on a site but user can't view site. User needs access to SharePoint site.
If you do not know who the site administrators are, contact firstname.lastname@example.org.
More resources can be found on the SharePoint webpage here: http://www.siue.edu/its/sharepoint/