Query 1: How can I get acces to SharePoint central administration (do I have to be a site admin?)
Two sets of users are allowed to perform administrative functions for Microsoft.
1. Members of the administrators group for the local server computer.
This can be done from "Active directory users and computers" program. Open "Active directory users and computers" on server--> Click on Built-in groups --> Find Administrators group --> Add member.
Members of the Administrators group on the local server computer have full control of all applications running on that server, including Internet Information Services (IIS), Microsoft SQL Server, Microsoft ASP.NET, and . These administrators can perform any task on that server, including all administration tasks for , such as controlling administrative functions, configuring settings at the server or virtual server level, and creating or changing sites and lists.
2. Members of the SharePoint administration group.
This can be done from SharePoint central administration itself. & can only be done by admin of central admin. Go to SharePoint central administration site --> Click on Security--->Manage the farm administrators group---> Add user
Members of the SharePoint administration group can perform SharePoint Central Administration tasks, but do not have access to the file system of the server or the IIS metabase, so they cannot perform actions on other applications running on the server, such as IIS, Microsoft SQL Server, ASP.NET.
So, Member of any above group can able to access SharePoint central administration.
Query 2: How to check who is site admin?
You can find it using following two ways
1. Site Setting:
Go to site setting ---> Users and Permissions ---> Site collection administrators (Site Collection Administrators are given full control over all sites in the site collection. )
2. Central administration:
Go to central administration --> Application Management --> Change Site Collection Administrators (change site collection from site collection drop down to check respective site collection admin)