pagination in custom query

Hi Everyone,

i am make one function in function.php file in which i wrote my own query. now i want set pagination(bbpress pagination). i dont know about and any idea. please help me . below my function.

function best_conversationstarters(){
	global $wpdb, $paged, $max_num_pages;

    $paged = (get_query_var('paged')) ? get_query_var('paged') : 1;
    $post_per_page = (intval(get_query_var('posts_per_page'))>0) ? intval(get_query_var('posts_per_page')) : 5;
    $offset =  ($paged - 1)*$post_per_page;
	
	$best_conversation_starter =  "SELECT COUNT(*) topic, post_author FROM {$wpdb->posts} WHERE {$wpdb->posts}.post_type LIKE '%topic%' GROUP BY post_author ORDER BY topic DESC LIMIT ".$offset.", ".$post_per_page;
	$sql_result = $wpdb->get_results( $best_conversation_starter, OBJECT);
	
	/* Determine the total of results found to calculate the max_num_pages
     for next_posts_link navigation */
    $sql_posts_total = $wpdb->get_var( "SELECT FOUND_ROWS();" );
    $max_num_pages = ceil($sql_posts_total / $post_per_page);

    return $sql_result;
}

thanks.