Trimming
To remove the tough bottoms from asparagus, gently bend the ends.  They'll break off where the tough woody section begins.  You may also want to peel the fibrous green portion from the bottom part of the stalks.

Cooking
Lay the asparagus in a large while saucepan half filled with boiling salted water.  Return the water to a gentle boil and cook for 5 to 8 min. or until the asparagus is bright green but not limp.  Do not overcook.  To steam, wind string loosely around bundles of 6 to 10 spears and stand, stalk end down, in a tall narrow pot with a few inches of water.  Cover tightly and boil for 10 to 15 min.  The tough ends cook in the water while the tender tops steam.