Main does not contain a constructor that takes 0 arguments

Question

namespace Patient_Information_System

{

    public partial class Doctors : Form

    {

        

        public Doctors()

        {

            InitializeComponent();

        }

        private void button1_Click(object sender, EventArgs e)

        {

            this.Hide();

            Main f2 = new Main();

            f2.ShowDialog();

        }

    }

}

I get the error there. 
Here is my main code.

namespace Patient_Information_System

{

    public partial class Main : Form

    {

        

        public Main(string UserName)

        {           

            InitializeComponent();

            label11.Text = UserName;

            toolStripStatusLabel2.Text = UserName;

            timer1.Start();

            load_usertbl();

        }

I cant seem to fix it :/ Ive tried placing the username string outside the main part.