Your connection string is wrong:
SqlConnection conn = new SqlConnection("Data Source=.;Initial Catalog=Resort;Integrated Security=True");
Check it: In VS open the Server Explorer pane. Click on your Database name, and look at the "Connection String" property in the Properties Pane: If necessary, Right click, "Select All" and copy, then paste it into your app.
Later, you will probably want this in a settings file - not difficult, and Google can help you there!