Ok you'll want all your different sprites as animation frames of a single sprite object.
For that sprite object, you want to add two instance variables: A numerical "Pair" variable, so you can determine which sprites are matches (each set of two should have a unique value greater than 0), and a "Selected" boolean, which you can toggle so you can't pick the same sprite twice.
You'll also need a single global variable, to keep track of which "Pair" is currently of interest.
Here are the events: