Hooks and templates problem

[cereal2nd]

hey,

i'm trying to write a custom product for my site, but for this to work i need to add a container like the announcement container to every single page ....

Now i created the admincp parts and i registered a hook (parse_templates) where i run the php code. But now i'm lost, where do i go from here? How do i get the ouput that i generated inside the hook on the screen? What do i have to do to get the output displayed inside the templates?