page navigation from address bar

Hi all,
I have developed a website and the home page is complete.Now when I navigate the pages from menu bar,it shows everything correct but when I copy and paaste the name of the page on the addressbar.corresponding to the namew of the site,it again navigates to the particular page.I don't want that when I copy and paste the page name in the address bar,i should navigate to that page rather i should navigate to home page.
What is the solution.Is there any?
eg:my wesite name is [email protected]/HomePage.aspx
now i copy the contactus.aspx page on the HomePage.aspx and i press enter,then I should navigate to homepage rather contatc us page.
Thanks in advance