CSC-SY

To handle this in your code you have to do the following
A put this between your head tags

    <link title="Site Title" rel="search" type="application/opensearchdescription+xml" href="/xmlFile Path" />

B You have to build the XMl file

<?xml version="1.0" encoding="Site Encoding"?>
 <OpenSearchDescription xmlns="http://a9.com/-/spec/opensearch/1.1/"
 			xmlns:moz="http://www.mozilla.org/2006/browser/search/">
   <ShortName>Site Short Name</shortname>
   <LongName>Site Long Name</longname>
   <Description> Site Description </description>
   <Developer> Whatever</developer>
   <Attribution> CopyRights</attribution>

   <SyndicationRight>open</syndicationright>
   <Contact> Site Email</contact>
   <Tags>   ---   </tags>
  <InputEncoding>Site Encoding</inputencoding>
  <OutputEncoding>Site Encoding</outputencoding>
  <Image width="16" height="16">Image Icon code </image>

  <AdultContent>false</adultcontent>
  <Query role="example" searchTerms="lebanon" />
  <Image height="16" width="16" type="image/x-icon"> Site Icon full path</image>
  <Language>ar</language>
  <Url type="text/html" template="http://www.sitename.com/searchPage?q={searchTerms}"/> 
  <moz:SearchForm>http://www.sitename.com/searchPage</moz:searchform>
 </url></query></opensearchdescription>

Now when anybody visits your sites the option to add it to the search engine list in firefox is available for him/here,
try click the list and you will find a choice that says add "Site"
I Hope this helps

Thank you hanihh ... Fixed

Thanks that was helpful.
I knew it's really simple to implement, but I don't know why it didn't cross my mind to actually implement it for this site
And since kobaitari has already implement it, I think we should use his implementation.