Singleton connection class with C# (ADO.NET)

Connection.cs

using System.Data.SqlClient;

namespace Project.Infra
{
    // Singleton Class
    class Connection
    {
        // Connection's configuration:
        private static string connectionString = @"YOUR-CONNECTION-STRING";
        private static Connection singleton;
        private static SqlConnection sqlConnection;

        public SqlConnection SqlConnetionFactory
        {
            get { return sqlConnection; }
        }

        private Connection() { }

        public static Connection Singleton
        {
            get
            {
                if (singleton == null)
                    singleton = new Connection();

                sqlConnection = new SqlConnection(connectionString);
                return singleton;
            }
        }

    }
}

Hello,
While using this singleton class, how can we create an instance in order to send request to the database?

Regards