call one event before the other

I have the following piece of code.
The problem I am having is that I need the btn.Click event to happen before the btn.Attributes.Add new window is opened.
The way it works at the moment is that the dialog box opens and when clicking off it the btn.Click event is called. I need it to work the other way round
Does anyone know how I can merge these to together?
 
Thanks
btn.Click += _presenter.Create; btn.Attributes.Add("onclick", "window.showModalDialog('Note.aspx?Id=" + Id + "', '', 'center:yes;resizable:yes;dialogHeight:800px;dialogWidth:750px;scroll:on;'); ");

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