In brief

Sampajana - the quality of non-obliviousness in regards to what one is doing and what is being experienced.

Cittanupassana is a discernment, contemplation & attending to the qualities & states pertaining to what is called mind, consciousness or intellect.

Dhammanupassana is a discernment, contemplation & attending to states & qualities pertaining to the teachings of the Buddha. 

As an example one might be sitting ardent & alert in seclusion, clearly comprehending what is going on, that is one's sampajana.

Being secluded from unwholesome qualities one might experience joy & pleasure born of seclusion.

At that time one might take note of the mind being gladdened, that is one's cittanupassana.

Furthermore one might discern that very gladness as a factor of enlightenment present in him, that is one's dhammanupassana.