After form submission want to show success message in the form page

Admin side I submit form to admin-post.php. I want to print success message in the bottom of the form. Iam new in wordpress what i did shown below.

admin.php?page=add-products form code

 form action="?php echo admin_url('admin-post.php') ?" method="post"
                table
                input type="hidden" name="action" value="add_product_from_admin"
                trtdName/tdtdinput type="text" name="pr_name" id="pr_name"/td/tr 
    trtd colspan="2" align="center"input type="submit" name="pr_submit" id="pr_submit" value="Save Products"/td/tr
                /table
            /form


    add_action( 'admin_post_add_product_from_admin', 'add_product_into_data_base' );



function add_product_into_data_base() {
    //some database operations
wp_redirect(admin_url('admin.php?page=add-productsmessage=success'));
}