Playing music with a micro SD card reader and speaker

I have just purchased an 8 ohm speaker and a micro SD card reader. The pins on the reader are 3v3,CS,MOSI,CLK,MISO,GND. I know you plug 3v3 to 3v3 on the arduino and GND to GND on the arduino, but which pins go into the speaker and what are the remaining two pins for?

Do NOT connect the speaker directly! The minimum resistance (or impedance) on an Arduino pin is 125 Ohms. (The "absolute maximum" current is 40mA and you can calculate the resistance using Ohm's Law.)

You can put a resistor in series with the speaker (which will lower the volume), use a Piezo transducer instead of a speaker, or you can use "powered" computer speakers.

The speaker gets connected to whatever output pin your software uses (and ground).

what are the remaining two pins for?

Two pins on what?