How to connect to Oracle DB from .NET?

Try following connection string

string con = "Data Source=(DESCRIPTION =(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST = 000.00.0.00)(PORT = 0000)))(CONNECT_DATA =(SERVICE_NAME = database)));User ID=User/Schema;Password=password;Unicode=True";

& then use this conection string as follow

using (OracleConnection objConn = new OracleConnection(con))
 {
   \\ code
 }

I highly recommend using the "Official Oracle ODP.NET, Managed Driver".

https://www.nuget.org/packages/Oracle.ManagedDataAccess/

Or the one for Entity framework: https://www.nuget.org/packages/Oracle.ManagedDataAccess.EntityFramework/

After installing via Visual Studio it opens a readme that I also recommend you read.

Oracle provide massive amounts of documentation. This is where to start: http://www.oracle.com/technetwork/topics/dotnet/whatsnew/index.html