jwashburn on "Having trouble with adding content to top of post using add_filter"

I have a plugin that I am working on hacking a bit. Currently it pulls some data and adds content to the bottom of a post using
add_filter('the_content', 'showWhiteboard');

It also uses add_filter( 'page_template', 'wodtogether_page_template' );

to grab the page template

It works fine, no problems with it. I am trying to get it post the data at the TOP of the post, right now its appending to the post. I have been reading the documentation http://codex.wordpress.org/Plugin_API/Filter_Reference/the_content

and trying to understand priority but I dont think I have a handle on it yet. I tried editing the line from

add_filter('the_content', 'showWhiteboard');

to

add_filter('the_content', 'showWhiteboard', '5'); to make it show up before the actual regular post content, but it doesn't really change anything

Can I get a shove in the right direction?

Thanks