[help]registration errors hellp!!

i did evry thing that it says in the tutorials
and i allways get this
Fatal error: Call to undefined function: mssql_connect() in c:\appserv\www\config.php on line 22

or this

Fatal error: Call to undefined function: mssql_connect() in c:\appserv\www\config.php on line 47

and other stuff like that..

wat can be the posible problems?
if u have a solution please post her and tell me how to do it...
please hellp me ime dieng here!!!!!!!!!

another question ..
what is my "Database Host" where i need to find it?