How to calculate percentage for ram(memoryusage)

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C#

I have 2 queries.
I have created working with cpu monitoring, I have retrieved value for CPU Usage, Ram Usage(memory), were as CPU usage has been calculated in percentage.

1. I need Memory Usage as Percentage value. I have tried but i couldn't reach.

2. When i host this application in Windows Service, How i can identify which machine usage consumption.

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }
    static List<float> AvailableCPU = new List<float>();
    static List<float> AvailableRAM = new List<float>();
    protected static PerformanceCounter cpuCounter;
    protected static PerformanceCounter ramCounter;
    private void Form1_Load(object sender, EventArgs e)
    {
        cpumonitor("CL35");
    }
    public void cpumonitor(string machinename)
    {
        cpuCounter = new PerformanceCounter();
        cpuCounter.CategoryName = "Processor";
        cpuCounter.CounterName = "% Processor Time";
        cpuCounter.InstanceName = "_Total";
        //string machinename = System.Environment.GetEnvironmentVariable("COMPUTERNAME");
        cpuCounter.MachineName = machinename;
        ramCounter = new PerformanceCounter("Memory", "Available MBytes");
        try
        {
            System.Timers.Timer t = new System.Timers.Timer(5000);
            t.Elapsed += new ElapsedEventHandler(TimerElapsed);
            t.Start();
            Thread.Sleep(10000);
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message, "catched exception");
        }
    }
    public static void TimerElapsed(object source, ElapsedEventArgs e)
    {
        float cpu = cpuCounter.NextValue();
        float ram = ramCounter.NextValue();
        MessageBox.Show(string.Format("CPU Value: {0}, ram value: {1}", cpu, ram));
        AvailableCPU.Add(cpu);
        AvailableRAM.Add(ram);
    }
}

What I have tried:

I have tried for getting total memory usage.

public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        static List<float> AvailableCPU = new List<float>();
        static List<float> AvailableRAM = new List<float>();
        protected static PerformanceCounter cpuCounter;
        protected static PerformanceCounter ramCounter;
        protected static PerformanceCounter ramTotMB;
        private void Form1_Load(object sender, EventArgs e)
        {
            cpumonitor("CL35");
        }
        public void cpumonitor(string machinename)
        {
            cpuCounter = new PerformanceCounter();
            cpuCounter.CategoryName = "Processor";
            cpuCounter.CounterName = "% Processor Time";
            cpuCounter.InstanceName = "_Total";
            //string machinename =           System.Environment.GetEnvironmentVariable("COMPUTERNAME");
            cpuCounter.MachineName = machinename;
            ramCounter = new PerformanceCounter("Memory", "Available MBytes");
            ramTotMB = new PerformanceCounter("Memory", "Total MBytes");
            try
            {
                System.Timers.Timer t = new System.Timers.Timer(5000);
                t.Elapsed += new ElapsedEventHandler(TimerElapsed);
                t.Start();
                Thread.Sleep(10000);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "catched exception");
            }
        }
        public static void TimerElapsed(object source, ElapsedEventArgs e)
        {
            float cpu = cpuCounter.NextValue();
            float ram = ramCounter.NextValue();
            float Totram = ramTotMB.NextValue();
            MessageBox.Show(string.Format("CPU Value: {0}, ram value: {1},Totalvalue: {2}", cpu, ram,Totram));
            AvailableCPU.Add(cpu);
            AvailableRAM.Add(ram);
        }
    }