private void RegisterLink_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e)
{
var reg = new UserRegister();
panel1.Controls.Add(reg);
reg.Dock = DockStyle.Fill;
//reg.Anchor = AnchorStyles.Left | AnchorStyles.Right | AnchorStyles.Top;
//reg.Width = panel1.Width;
reg.BringToFront();
}