help in magento with wordpress function

I am new to magento and what i have magento wordpress by figpig installed.After much research i found that wordpress functions won't work in magento. As my function was placed in theme folder, which would display thumbnails in rss as well as turn hyperlinks in post.

As i am new to magento, i want to convert the following function to make it work and where to use it? I already have it wordpress function.

    add_filter( 'the_excerpt_rss', 'insert_thumbnail_into_feed' );
add_filter( 'the_content_feed', 'insert_thumbnail_into_feed' );


function insert_thumbnail_into_feed() {
    global $post;
    if ( has_post_thumbnail( $post-ID ) ){
        // replace thumbnail with yours
        $content = 'p' .get_the_post_thumbnail( $post-ID, 'thumbnail' ) .'/p';
    }

    // get post content and replace feed content with
    // you can also limit/filter the content to exclude shortcodes and html code etc.
    $content .= 'p' .get_the_content() .'/p';

    return $content;
}

also if someone can point me in right direction to learn about magento development wise.