Create some static class file suppose Class1
Declare static variable in that.
Public static string strColumn;
In first form use static variable.
Private void button1_Click(object sender, EventArgs e)
{
Class1.strColumn = txtColumn.Text;
Form2.Show();
}
Second form Coding
Private void Page_load((object sender, EventArgs e))
{
string q = ("select SEC_QUESTION from Table1 where USERNAME='" + Class1.strColumn + "'");
}