Adding/reading Information from Database (Login/Register) problems

Question

If i'm somehow in the wrong forum please say so.

For the past day I have been trying to create a register/login system.
Where a user submits the data where it gets stored on a table. Then the user submits the information to login.

Heres the problem. The information is not being stored. I don't have much experience with SQL, so doing what I usually do with something I don't know, I youtube it.
And that ultimately left me with this project here.


Note: Yes I did test the connection and it was connected. 

any help is appreciated

Register Form

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

using System.Data.Sql;

using System.Data.SqlClient;

namespace Login_Database

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

        }

        private void Form1_Load(object sender, EventArgs e)

        {

            

            string connection = @"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database1.mdf;Integrated Security=True;User Instance=True";

            SqlConnection cn = new SqlConnection(connection);

            try

            {

                cn.Open();

            }

            catch

            {

                MessageBox.Show("Could not connect");

            }

        }

        private void button1_Click(object sender, EventArgs e)

        {

            Form2 form2 = new Form2();

            form2.Show();

            

            string connection = @"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database1.mdf;Integrated Security=True;User Instance=True";

            SqlConnection cn = new SqlConnection(connection);

            try

            {

                cn.Open();

            }

            catch

            {

                MessageBox.Show("Could not login");

            }

            string username = textBox1.Text;

            string password = textBox2.Text;

            string sqlquery = ("SELECT * FROM User WHERE Username = '" + textBox1.Text + "'");

            sqlquery = "INSERT INTO [User] (Username, Password) VALUES ('" + textBox1.Text + "','" + textBox2.Text + ")";

            SqlCommand command = new SqlCommand(sqlquery, cn);

            command.Parameters.AddWithValue("Username", username);

            command.Parameters.AddWithValue("Password", password);

            command.Parameters.Clear();

            

            

            

        }

        private void button2_Click(object sender, EventArgs e)

        {

            Form2 form2 = new Form2();

            form2.Show();

            Form1 form1 = new Form1();

            form1.Hide();

        }

    }

}

Login Form

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

using System.Data.Sql;

using System.Data.SqlClient;

namespace Login_Database

{

    public partial class Form2 : Form

    {

        public Form2()

        {

            InitializeComponent();

        }

        private void button1_Click(object sender, EventArgs e)

        {

            string connection = @"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database1.mdf;Integrated Security=True;User Instance=True";

            SqlConnection cn = new SqlConnection(connection);

            try

            {

                cn.Open();

            }

            catch

            {

                MessageBox.Show("Could not connect");

            }

            SqlCommand cmd = new SqlCommand("SELECT * FROM [USER]", cn);

            cmd.Connection = cn;

            SqlDataReader reader = null;

            reader = cmd.ExecuteReader();

            while (reader.Read())

            {

                if (textBox1.Text == (reader["Username"].ToString()) && textBox2.Text == (reader["Password"].ToString()))

                {

                    MessageBox.Show("Logged In");

                }

            }

        }

    }

}