Simple Ajax Search Engine with Ip Location & Filter

Go to [login to view URL] for a general idea of what I am thinking of. Must pull city from visitors IP address and put that at the Searching: If users want to change that location they can press change location and a ajax box will pop up with a list of different cities / countries. They can scroll through them all or type in an input which would auto search the whole list for fast results. Then once they select the new location the Searching: will change via ajax to the place they selected (and be highlighed showing that the search filter is the city instead of nationwide) If they dont want to search by city and instead search by nation they can simply click Search Nationwide (which will highlight that telling the user that the filter for nationwide is set). They can also click on a category which will highlight the category they clicked on. Once they press search the page will go to [login to view URL],etc with all the preferences they selected via ajax. I will code the search page, I just dont know ajax and I want the homepage search filter to run off ajax with those preference. Notice that when they choose a location to search or category that it should be highlighted letting the user know that they successfully selected a filter. The page shouldnt refresh with the preference changes. Any questions feel free to ask, this should be relatively straight forward project if you know ajax. I should also know the source to update the databases ip city, country list.