how to make it so my facebook friends don't see my activity?

[tarun]

All you need to do is visit your profile and begin
hiding the various story types that you don’t
want others to see.
Say, for example, that you don’t want others to
see the comments that you write your friends’
profiles on Facebook. Scroll down through your
profile until you see one of your previous
comments and click on the “X.”
Facebook will then prompt you with a
confirmation box, to make sure that you really
want to hide all comments (which you probably
do). Just click “Hide All”, and now all your
comments will be hidden.
Simply continue to hide all recent activities on
events you’ve RSVPed to, or any other recent
activity types that you want to hide.
If you want to modify these settings at any time
(and re-display content that was previously
hidden), you can scroll down to the bottom of
your profile feed and click on “Edit Options.”