Arduino Nano Speaker Setup

Hi, I am new to arduino and directly went for a nano.
Im aiming for an IoT kind of use for the arduino, going to be controlling switches and circuits via relays, and also connectinf an rgb led strip, 5m, I have got all of this figured out via the great guides out there.

Now what i was wondering was, I have an old speaker lying around, which i savaged from wireless speakers I had once, the speakers have nothing printed on them, but I was wondering if I wud be able to use them with the arduino and what steps I wud need to take?? I see many simple audio player guides, but i do not know if i can directly connect this speaker, or if i need something else for it to function.

Also would it also be possible to play songs via the server of Esp8266??

Thank you

If you want something more than minimal volume you ‘wud’ need an amplifier to drive the speaker.
A Nano output can only provide 20-25mA of current into a 200 ohm load - measure the resistance of your speaker terminals, you will likely get a reading of ~ 4, 8, 16, 32 ohm. Add a resistor in series to total 150-200 ohm, and that’s what the Nano can drive. It won’t be very loud, just 125mW split proportionally between the resistor and the speaker.
Pick up a pair self-powered computer speakers and let the Nano drive that instead.
http://www.parts-express.com/cat/multimedia-computer-speakers/3406
You can hear what that will sound like here and see the schematic to connect an output pin to the speaker input.

If you want to play real music vs making your own tones, then you need a SD-based sound module that the Nano can control such as
rMP3 Playback Module – Rogue Robotics or similar from Adafruit.com

Playing music from ESP8266 - I don’t have any experience there. I imagine you’d have to get the data and send it to a VS1053B MP3 decoder, or send raw .wav data to a pair of DACs or something.