Formsapi, how to build a custom site after submit

Hello,

I use the forms-Api to build a new form to search data in my module and validate it.
It looks something like:

function f1() {
    return drupal_get_form('my_form');
}
function my_form($a) {
    //return some formarray
}
function my_form_validate($a) {
   //some validation
}
function my_form_submit($a,$b) {
   //processing
   return $coolcontent;
}

But additionally to processing the searchrequest, I want to display the result of it. But returning content from this function does not work.
How can I achieve, that my processed data can be displayed. I tried to play with the $form_state-array, but I didn´t come to a result.

Thanks in advance.