using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var myNewInstance = new KrepselisClass();

        KrepselisClass.KrepselisList.Add(myNewInstance);

        // OR

        KrepselisClass.KrepselisList.Add(new KrepselisClass());

    }

}

​

public class KrepselisClass

{

    public static List<KrepselisClass> KrepselisList = new List<KrepselisClass>();

}