Hi I want to know that is there any kind of interface or place where I can update my WordPress theme without showing it to others? For example localhost is used to update websites, but it won't work with WordPress blogs because they contain own made functions, for example getheader(). If you know any kind of interface or place please tell me.
You can always set up a dummy site to test on- just make a subdomain on your site and install a new copy of Wordpress there, which you can mess with. You can also download software to simulate mysql on your local system.
there is a plugin that lets u switch try out new themes without others seeing the new layout.. i believe it is called theme switcher (it's free)