A small help in understanding structs:

using System;
using static TestStuff.Class2;

namespace TestStuff
{
    internal class Program
    {
        static void Main(string[] args)
        {
            var testHoldStruct = new TestHold();
            var testHoldStruct2 = new TestHold2();

            testHoldStruct.val1 = 100;
            testHoldStruct.val2 = 500;

            testHoldStruct2.val2_1 = 1000;
            testHoldStruct2.val2_2 = 5000;

            Class1.ProcessTest(testHoldStruct, testHoldStruct2);

            Console.WriteLine("");
            Console.WriteLine("Done");
            Console.ReadLine();
        }
    }
}

using System;
using static TestStuff.Class2;

namespace TestStuff
{
    internal class Class1
    {
        public static void ProcessTest(TestHold testHoldStruct, TestHold2 testHold2Struct)
        {
            Console.WriteLine(testHoldStruct.val1);
            Console.WriteLine(testHoldStruct.val2);

            Console.WriteLine(testHold2Struct.val2_1);
            Console.WriteLine(testHold2Struct.val2_2);
        }
    }
}

namespace TestStuff
{
    internal class Class2
    {
        public struct TestHold
        {
            public int val1;
            public int val2;
        }

        public struct TestHold2
        {
            public int val2_1;
            public int val2_2;
        }
    }
}