You'll need to set the URL for the control during the OnInit phase of the page/control lifecycle because it has some hard-coded stuff into PageLoad on the control that makes it impossible to change the URL later. In a nutshell:
protected override void OnInit(EventArgs e)
{
UrlControl1.Url = "someSetting"; // where some setting is whatever you have saved to your database from a previous UrlControl.Url reading
}
You can also change the type by setting UrlControl1.UrlType = "N" (none), "F" file, "U" user, "T" tabs