Como fazer um botão de editar formulário em c sharp?

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using SistemaSinos.DAL;

namespace SistemaSinos
{
    public partial class frmUsuarios : Form
    {
        public frmUsuarios()
        {
            InitializeComponent();
        }

        private void frmUsuarios_Load(object sender, EventArgs e)
        {
            this.usuarioBindingSource.DataSource = DataContextFactory.DataContext.Usuario;
        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            CurrencyManager cm = (CurrencyManager)BindingContext[usuarioDataGridView.DataSource];
            cm.EndCurrentEdit();
            cm.ResumeBinding();
            cm.SuspendBinding();

            var termo = (sender as TextBox).Text.ToLowerInvariant();
            bool semTermo = String.IsNullOrEmpty(termo);

            foreach (DataGridViewRow linha in usuarioDataGridView.Rows)
            {
                if ((linha.Cells[dataGridViewTextBoxColumn4.Index].Value as string).ToLowerInvariant().Contains(termo) || semTermo)
                    linha.Visible = true;
                else
                    linha.Visible = false;
            }
        }

        private void btn_cancelar_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        private void btn_novo_Click(object sender, EventArgs e)
        {
            frmUsuariosAdd frm = new frmUsuariosAdd();
            frm.Show();
            this.Close();
        }

        private void btn_excluir_Click(object sender, EventArgs e)
        {
            
            if (MessageBox.Show("Tem certeza que deseja excluir esse funcionário?", "Confirmação", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes)
            {
                this.usuarioBindingSource.RemoveCurrent();
                DataContextFactory.DataContext.SubmitChanges();
                MessageBox.Show("Funcionário/usuário excluído com sucesso!");
            }
        }

        private void button1_Click(object sender, EventArgs  e)
        {
            try
            {
                
            DataGridViewRow linha = new DataGridViewRow();
            linha = usuarioDataGridView.CurrentRow;
            frmUsuariosEdt alt = new frmUsuariosEdt();


            alt.preencher(
            linha.Cells["dataGridViewTextBoxColumn4"].Value.ToString(), //id
            linha.Cells["dataGridViewTextBoxColumn4"].Value.ToString(), //nome
            linha.Cells["dataGridViewTextBoxColumn7"].Value.ToString(), //email
            linha.Cells["Senha"].Value.ToString(), //senha
            linha.Cells["dataGridViewTextBoxColumn5"].Value.ToString(), // situacao
            linha.Cells["dataGridViewTextBoxColumn6"].Value.ToString(), // sexo
            linha.Cells["dataGridViewTextBoxColumn8"].Value.ToString(), //endereco
            linha.Cells["dataGridViewTextBoxColumn9"].Value.ToString(), //numero
            linha.Cells["dataGridViewTextBoxColumn10"].Value.ToString(), //bairro
            linha.Cells["dataGridViewTextBoxColumn11"].Value.ToString(), //cep
            linha.Cells["dataGridViewTextBoxColumn12"].Value.ToString(), //cidade
            linha.Cells["dataGridViewTextBoxColumn13"].Value.ToString(), //estado
            linha.Cells["dataGridViewTextBoxColumn14"].Value.ToString()); //fone 
            alt.ShowDialog(this);
            }
            catch
            {
                MessageBox.Show("Não é possivel alterar um registro inexistente, clique em Incluir para inserir um novo!", "Erro", MessageBoxButtons.OK, MessageBoxIcon.Error, MessageBoxDefaultButton.Button1);
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using SistemaSinos.DAL;


namespace SistemaSinos
{
    public partial class frmUsuariosEdt : Form
    {
        public frmUsuariosEdt()
        {
            InitializeComponent();
        }

        private void frmUsuariosEdt_Load(object sender, EventArgs e)
        {
         
            this.usuarioBindingSource.DataSource = DataContextFactory.DataContext.Usuario;
            

        }

        public void preencher(string idUsuario, string dataGridViewTextBoxColumn4, string dataGridViewTextBoxColumn7, 
        string Senha, string dataGridViewTextBoxColumn8, string dataGridViewTextBoxColumn9, string dataGridViewTextBoxColumn10, 
        string dataGridViewTextBoxColumn12, string dataGridViewTextBoxColumn11, string dataGridViewTextBoxColumn13, 
        string dataGridViewTextBoxColumn6, string dataGridViewTextBoxColumn5, string dataGridViewTextBoxColumn14)
        
        {
            //parametros para passar os dados do grid
            idUsuarioTextBox.Text = idUsuario;
            nomeTextBox.Text = dataGridViewTextBoxColumn4;
            senhaTextBox.Text = Senha;
            emailTextBox.Text = dataGridViewTextBoxColumn7;
            enderecoTextBox.Text = dataGridViewTextBoxColumn8;
            numeroTextBox.Text = dataGridViewTextBoxColumn9;
            bairroTextBox.Text = dataGridViewTextBoxColumn10;
            cidadeTextBox.Text = dataGridViewTextBoxColumn12;
            cepTextBox.Text = dataGridViewTextBoxColumn11;
            estadoTextBox.Text = dataGridViewTextBoxColumn13;

            sexoComboBox.Text = dataGridViewTextBoxColumn6;
            situacaoComboBox.Text = dataGridViewTextBoxColumn5;
            foneTextBox.Text = dataGridViewTextBoxColumn14;

            
        }

        private void btn_salvar_Click(object sender, EventArgs e)
        {
            
            DataContextFactory.DataContext.SubmitChanges();
            MessageBox.Show("Usuário editado com sucesso!");
            this.Close();
            frmUsuarios frm = new frmUsuarios();
            frm.Show();
        }
    }
}