Sir , database doesnot get id value automaticaly?

See more:

C#

ASP.NET

if we doesnot enter the id value than error is comes
previously the doesnt occurs but when i update the vs then it happens
give me solution plzzz please

What I have tried:

try
      {

            SqlConnection con = new SqlConnection("Data Source=VIDYA\\SQLEXPRESS;Initial Catalog=EExamData;Integrated Security=True");
            SqlDataAdapter da = new SqlDataAdapter();
            SqlCommand cmd = new SqlCommand("insert into Signup(Name,Gender,Email,Password) values('" + name.Text + "','" + Gender + "','" + emailid.Text + "','" + passward.Text + "')", con);
            con.Open();
            cmd.ExecuteNonQuery();
            con.Close();

            
            
            lbl_error.Text = "Successfully Registered";
        }
        catch(Exception ex)
        {
            Response.Write("Error" + ex);
        }

tableconsist of:id(primary key),name,gender,email_id,password