This article is from the Recreational Figure Skating FAQ, by Karen Bryden with numerous contributions by others.
The easiest stop is a snowplow, in which you turn your toes toward
each other in a V, then put pressure on one of the blades (the right
will probably feel better) so that it skids sideways along the ice
(instead of gliding ahead), and slows you down. Try not to lean
forward or tip onto your toes when doing this. It may help if you
first bend your knees and think in terms of pushing your heel out,
rather than turning your toe in.