If you want to add a new page under the forum menu, you should use wpforo_page hook with Insert Page plugin.

1. Create the page in WordPress pages admin page, and find the page ID in the address bar:

2. Install the Insert Page plugin

3. Add the following hook code in your current active WordPress theme, or install the Code Snippets plugin and add new PHP code snippets in the plugin admin page:

function wpforo_page_new_page_1( $template ){
    if( $template == 'new-page' ){
        ?>
        <div class="wpforo-page wpforo-page-1 wpforo-text">
            <?php echo do_shortcode("[insert page='11105' display='content']"); ?>
        </div>
        <?php
    }
}
add_action( 'wpforo_page', 'wpforo_page_new_page_1', 10 );

Don't forget to change the 11105 ID to your page ID. Also, you can change the "new-page" slug to any phrase without spaces and special symbols. The new-page slug is used in the custom page URL

4. The new forum page URL will be :

 https://example.com/community/?wpforo=page&view=new-page 

5. You can add this page to wpForo menu, go to Dashboard > Appearance > Menus admin page, select wpForo Navigation in the drop-down, Use Custom Link to add a new menu item:

• URL: https://example.com/community/?wpforo=page&view=new-page
• Menu Text: New Page