Create a new admin panel?

Beginner question here: I am developing my first plugin and I want to add a new panel to the admin horizontal nav bar. filterAdminNavigationMain works perfectly to initiate the nav button but afterwards I get stuck in connecting it to a view (error 404). I am not yet at ease with using the controller and the previous discussions on the topic (here and there) were not completely clear for me.

For the time being my code on IndexController looks like this:

    public function indexAction()
    {
      $content_page = "<p>Just a test</p>"; /*Will hold a view later on but for a simple reproducible example*/
      $this->view->SplitPages = $content_page;
    }
}

An my code in the main plugin page is:

public function filterAdminNavigationMain($nav)
    {
        $nav[] = array('label' => __('SplitPages'), 'uri' => url('SplitPages'));
        return $nav;

}

I have looked in other plugins as well but I couldn’t locate the issue.