How do I populate fields on windows form at button click

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C#

SQL

I am trying to populate fields on the form on click of search button with stored procedure. At database level SP works fine. The textbox I am trying to search with is varchar type

private void btnsearch_Click(object sender, EventArgs e)
{
bool temp = false;
SqlConnection con = new SqlConnection("Data Source=xxxxxxxxxxx;Initial Catalog=xxxxxxxx;Trusted_Connection=true");
SqlCommand cmd = new SqlCommand();
cmd.CommandType = CommandType.StoredProcedure;
cmd.CommandText = "SP_name";


con.Open();
cmd.Connection = con;
cmd.Parameters.AddWithValue("@abc", txtabc.Text);
SqlDataReader dr = cmd.ExecuteReader();
while (dr.Read())
{
//need help with this part.
}
if (temp == false)
MessageBox.Show("not found");
con.Close();
}

I need help with populating other fields when user enters value into the textbox and click on search button if value exists in the db.

Thanks.