can't seem to add to menu

Hi, firstly forgive me I am completely new to all this.
I am trying to add pages to the menu and can't seem to figure it out. I've gone into 'Menus' under Themes, I've added posts into different categories to see if that would work. I did manage to get one on there (have no idea how) titled Local Businesses and it's showing test posts for some reason and not the actual Local Businesses page??
Now I don't know if it's me or the setting? Can someone help me please
the site is