script that canchange just one webpage

is there a script that will alow you to change just one page on the website here is my website http://avhorlando.net/ what i would like to do is when someone goes to http://avhorlando.net/1300 everypage on the original site http://avhorlando.net will stay the same execpt the reservations page which i would like it to go to http://secure.instantsoftwareonline....62&propid=1300 but still be iframed i need to do this for every property and was wondering if there is some way to do this without having to create 150 new pages. i am only familier with html so any help would be appreciated thanks