It's quite simple actually. Basically, you just pass a variable through the URL which your PHP page then examines and determines what to display based on its value.
If you look at the top of these forums in fact, you get a very good example of this kind of behaviour. For example, writing this post I'm at the URL http://www.frihost.com/forums/posting.php?mode=reply&t=78315
Now, obviously there is only posting.php page and not one created for every post! Now, after the page name you'll see that there is a ? which separates the page URL from the variables passed to it. It has two variables - "mode" (which is what I'm doing to the post - replying) and "t" (which is the topic number I'm replying to).
If you wanted to read these variables from PHP you'd do the following:
Hopefully that should give you enough of a start.
is so complicated way :
i want to know the way with case and break
You can do in this way:
Default will include english page what means if you didn't define language in URL.
For changing language you can use this links. Just change yoursite.com and index page in right page.