How to enable broswer Back and forward button on a flash site?

Hi all, please take a look at this site

If you try navigate around, the url window will change to|schk_xgzg|schc_4|pag_1 etc etc and the back and forword button seem to be working also, if you copy and paste the link, the flash will be smart enough to go to the indivual page also

My question is as below

  1. how do we make the back & forward button to work
  2. how do we contruct the url to be so dynamic

Any input is welcome!