Changing link on menu, but keeping the format of the button

First thing would be to activate the CSS option in your navigation.  To do this go to that screen, and in the top right corner is the “Screen Options” tab, click that and then select CSS and the description box.  After you do that you will be able to open the menu item and add the code needed to have the same styling.  Now go to the Custom Link option over where the pages are to add to the menu.  You can add the link to your booking spot, then name it what you want.  After it is added to the menu, open the item up and add iris-nav to the CSS Classes spot.  It will then automatically give it the same look as your Book With Me!  Let me know if you have any troubles.  We also have screenshots of this in the setup guide for the theme.