The gateway page is just the Osclass "Live Demo" main page located here:http://osclass.org/page/demo
You can take the source code from www.lenaweeproperty.com
if you want.
The source code can be copied and pasted into your editor. Then saved as index.html or index.php but is easier to edit if saved as an html document. Then just add, edit and remove whatever you want. place any text or image into the page then link the text or image to any page on any site.
You can place a link to any site login, register, search results page(s) or anything else you want.
If you look at the example at: www.lenaweeproperty.com
you will see images for "JOBS", "REALESTAE" and "CARS". Each image is linked to the index.php of a seperate installation of Osclass. All three could had been just linked to one installation but different search results pages such as if you have a cars catagory, chevrolet, impala then the cars image could be linked to the resulting impala page.
Once all the text and images are added and a linked on the gateway page, you should never have to edit them because the search result page link will always be there even if the content changes.
Being the gateway page is nothing more then html it is easily edited at any time. Best design would be a Jquery menu containing Main, sub, sub, sub catagories with each linked to a search result page. Using Jquery would allow for every possible link you could need.
An example of this menu can be seen here:http://demos.myjqueryplugins.com/jmenu/
Hover over catagory 1. Slide mouse down to the 3rd. catagory 1.2. Now slide down to the 2nd. catagory 1.3. Notice yet another catagory 1.4 opened. There can be unlimited number of "Sub_catagories". ALL these can be re-named and linked to any page so in reality you end up with multiple catagories and sub-catagories.
These links can go to any page located anyplace. If using the same database then only one Osclass installation is needed.
This is the easiest, simplest way to get mutiple catagory type results using Osclass.