using a add_action in wordpress to add php to sidebar or comments or below the Post

[bekk1n]

Hello,

I currently have a snippet that places code into the header of wordpress:

PHP Code:

if (!function_exists('function_name')){function function_name(){Insert Code Here}add_action('wp_head', 'function_name');} 


Does anyone know if I can use this modified to place php code into the sidebar? or Comments? or below the Post?

Or would I need a completely different snippet for it to work?