You said that you would discard the 6 of Clubs to say
that you want your partner to lead Clubs to you. This
is the correct answer. You picked an even card,
which is the signal that you want that suit back.
So so summarise the main ways of doing your best in defense
Lead well and meaningfully, and return partner's lead if
it is an encouraging one
Duck when you know the opposition are trying to lose their
Signal through discards which suit you want played back,
and which you don't want
Signal through high card play when following a suit, that
you want the suit returned.
Remember the bidding, and mentally decide whose hand the
missing cards are likely to be in.
Take advantage of things like hesitation before play - the
person who hesitates is making a decision, so must have a good card they
are trying to decide whether or not to play.
As much as you can, try to remember the cards that have
already been played, so that you know when a card is a boss.
Now go on to the next lesson, which is on the Stayman