Analog inputs

Very hard to meaningfully succeed with even a simple task when the MCU is as complex as LX4F.  There is a wealth of literature - datasheets and numerous code examples will give you a much better foundation so that you can attack your objective. 

We realize that the cost of this board was appealing - but the learning curve is not so discounted...  Many before have decided that ARM in general - especially Cortex M-4 - may not be the easiest - most efficient, "Starting Point."

Suspect that 3 major areas of learning are your targets: GPIO, ADC and MCU Set-Up/Configuration.  You need some understanding/mastery of each - to achieve your objective.  My belief is that a serious read of the MCU datasheet (yes - it is some 1400+ pgs.) - at least the GPIO, ADC and System Control chapters will give you far greater understanding.  After that - look for code examples which deal with GPIO, ADC and System Control.  (most all examples will detail how the System Clock is configured - you must be sure to "match" the value of the xtal on your board to the mating parameter w/in the System Control Clock configuration.

The ADC is likely the most complex of your 3 objectives.  Suggest that you "hold-off" with that - begin with System Control and GPIO - so that you can - at minimum - control your Led.  After that - you can "do battle" w/the ADC.