Forum:Card trader and spell counters

Excuse if my english is bad, but I have a question: Card trader puts a spell counter on card that can use them? My explanation is: card trader needs return a card from your hand to the deck to can draw a card. Until I have knowledge its a cost OF ACTIVATION AND NOT AND EFFECT, and, how card trader is activated, it puts a spell counter, for example in magical marionette. help me this my dude. I wrote right the question?