Insert records by user who's connected Winforms

Question

I have  a form  (F1) where user will provide their respective credentials username and password . After a sucessfull login , the controls moves to the Client Form (F2) and display welcome username in a label on it.

 

Client Form contains:

• labels and textboxes(name, address, function , ...)
• Button Insert
• DataGridView bind to DB (name, address, function ,.., UserId)
  
  

Now , I want to insert a Client

After filling textboxes, I want to add a Client a show it added by user who's connected.

 

Ex: if I logged with Username Rose after that add a client, in my datagridView , show me my row of insert added by Rose.

 Here is my code of Insert: 

private void button1_Click(object sender, EventArgs e)
      {
          if (  comboBox2.SelectedValue != null && textBox1.Text != string.Empty && textBox2.Text != string.Empty && textBox4.Text != string.Empty)
          {
              string cmdStr = "Insert into Client  (idUser,name,address,function,telephone,commentaire)values (@idUser,@name,@,address,@function,@telephone,@commentaire)";
              SqlConnection con = new SqlConnection("Data Source=User-PC\\SQLEXPRESS;Initial Catalog=timar;Integrated Security=True");
              SqlCommand cmd = new SqlCommand(cmdStr, con);
              con.Open();

             //The problem in this code how Can I get the id of username,Error cannot convert string Rose to int.
              cmd.Parameters.AddWithValue("@idUser",label.Text);
              cmd.Parameters.AddWithValue("@name", (comboBox2.SelectedValue));
              cmd.Parameters.AddWithValue("@,address", textBox1.Text);
              cmd.Parameters.AddWithValue("@function", textBox2.Text);
              cmd.Parameters.AddWithValue("@telephone", textBox4.Text);
              cmd.Parameters.AddWithValue("@commentaire",txtArchive.Text);


              int LA = cmd.ExecuteNonQuery();
              con.Close();
              MessageBox.Show("Le Client a été ajouter avec succés !","Saisie Rendez-vous", MessageBoxButtons.OK, MessageBoxIcon.Information);
              DisplayData();
              ClearData();
          }
          else
          {
              MessageBox.Show("Vérifier que tous les champs sont remplis !","Erreur",MessageBoxButtons.OK,MessageBoxIcon.Information);
          }
      }

 

I am not able to figure out how to do this, i am very new to c# and trying to learn.

Thanks in Advance .