Adding dynamicaly stylesheet with add_action(‘wp_head’,’…’)

hi all,

i’m trying, with no success, to use the add_action(‘wp_head’, ‘My_Header’) outside of a plugin, sure it doesn’t work but how to 🙂 ?

I don’t want to write a plugin for this. The case : i look for day and month and for certain date i add javascript function to show scrolling pictures and a symbolic picture for the event. But i want to place this picture in particular place function of event. So i add rules in a stylesheet where all my pictures (for all year’s events) positions are stocked. Now, in my “switch case” i’d like to be able to add the call of that stylesheet in the header. I’ve tried to use add_action(‘wp_head’, ‘My_Header’) but apparently it only works for call with plugins… So does someone knows a simply way to do that ?

TIA,

Flegme.