stuck on loop custom post_type

need help on the loop!

<?php query_posts('post_type=my_custom_posttype&showposts=-1&order=ASC') ?>
//all post are now displaying

//the taxonomy name is my_taxo and all post have its own category, item-1, item-2 etc.

//now i want to get from my_taxo each items and display its Name in ASC order (this is where i get stuck)

<?php //display the item-“x” name ?> //(in ASC order)
// then display all the post regarding this item”x”
<?php the_title(); ?>
<?php the_content();?>

and loop to the next item-“2” etc.

i am confused using
<?php if (have_posts()) : while (have_posts()) : the_post(); ?> incorrectly

have no idea how i can construct this correcly.
Anyone want to guide me in this please?