To display a child forms from your main application you have to first define your child forms in your application and call the following methods based on your need.
eg: This examples displays your child form as Model dialog which blocks the user to access the main form unless he/she close the child form.
private void child1Button_Click(object sender, EventArgs e)
{
Form2 testDialog = new Form2();
if (testDialog.ShowDialog(this) == DialogResult.OK)
{
}
else
{
}
testDialog.Dispose();
}
To display your child as Modeless dialog.
private void child1Button_Click(object sender, EventArgs e)
{
Form2 testDialog = new Form2();
testDialog.Show();
}