Replace back to top icon with an image

gistfile1.txt

if ( ! function_exists( 'generate_back_to_top' ) ) :
/**
 * Build the back to top button
 *
 * @since 1.3.24
 */
add_action( 'wp_footer','generate_back_to_top' );
function generate_back_to_top()
{
	$generate_settings = wp_parse_args( 
		get_option( 'generate_settings', array() ), 
		generate_get_defaults() 
	);
	
	if ( 'enable' !== $generate_settings[ 'back_to_top' ] )
		return;
	
	$scroll_speed = apply_filters( 'generate_back_to_top_scroll_speed', 400 );
	$start_scroll = apply_filters( 'generate_back_to_top_start_scroll', 300 );
	?>
	<a title="<?php _e( 'Scroll back to top','generatepress' ); ?>" rel="nofollow" href="#" class="generate-back-to-top" style="display:none;" data-scroll-speed="<?php echo $scroll_speed; ?>" data-start-scroll="<?php echo $start_scroll; ?>">
	  <img src="URL TO YOUR IMAGE" alt="" />
	</a>
	<?php
}
endif;