As you might've guessed, the IR transmitter is the simple part ... it's just like lighting an LED. The IR receiver is a little more difficult.
Look here to reference typical circuits involving an IR receiver ...
You can start with the simplest possible circuit for it ... it would go like:
+5 source -> IR receiver -> resistor -> ground
From the first schematic on the link I provided ... I'm basically describing the `left-half' of that circuit.
To ensure you'll never exceed the 30mA current rating of the IR receiver, you can't make your resistor any smaller than 166.666 ohms (from Ohms Law, V/I = R; 5V / 30mA).
The input for your ADC would come from between the IR receiver and the resistor. The idea is that when the IR receiver sees IR, it starts to conduct. This current flows through the series resistor and it drops a proportional amount of voltage. This voltage that you read across the resistor is proportional to the current flowing through it ... which is then related to the intensity of IR light that the IR diode is sensing.
This is basically a voltage divider where the IR diode acts as a variable resistor.
You're also going to want a small valued capacitor in parallel with the resistor ... say 1 nF or so ... which is meant to hold sense voltage while the ADC is actually sampling.
Once you get that simple circuit hooked up then you can actually start to take ADC readings ... and we can then figure out if the support circuit is sufficient and what you'll have to do to filter your readings to get the information you want.