.htaccess urgent help needed

I’m new to .htaccess .. so please I need your help ..
I need to create friendly search engine urls for my site [url]http://www.itcoursesonline.info[/url]
So I changed the urls in the mail categories( google – webdesign .. ) to look like this
[url]http://www.itcoursesonline.info/courses/all/59[/url] … and when clicked I want it to open the following url [url]http://www.itcoursesonline.info/courses/index.php?page=all_courses&cat_id=59[/url]

So I created a .htaccess file and I wrote this in it :

<IfModule mod_rewrite.c>
RewriteEngine on
Options +FollowSymlinks
RewriteRule ^{^/courses/all/([0-9]+)$} /courses/index.php?page=all_courses&cat_id=$1
</IfModule>

but this is not working …
please tell me exactly where to upload the .htaccess file .. and what shall I add inside it to solve this problem … I tried several resources on the internet .. and I donot know what is working and what is not .. I host my site with hostgator … and whenever I click my links I got page not found created by hostgator … I donot know if mode rewrite is working on my host or not .. please if any one has any idea .. let me know
thank you

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