Unless you provide a link to a page demonstrating the problem, no one will be able to offer much in the way of assistance.
Thanks esmi for pointing that out. I have half-solved the problem now.
At the bottom of the header tab in customize theme (Constructor) I unchecked the box “show search form” this has solved that issue.
I am still unable to add a new tab to my menu though. I want to add a “Links” page. I am bound to be be doing something wrong!
My website is “www.lezioninglese.com.