# fell on his face

He purposely lay face down on the ground to pray. 

# My Father

This refers to God the Father. It is best to translate “Father” with the same word that your language uses to refer to a human father. 

# let this cup pass from me

Jesus speaks of the work that he must do, including dying on the cross, as if it were a bitter liquid that God has commanded him to drink from a cup. The word "cup" is an important word in the New Testament, so try to use an equivalent for that in your translation. 

# this cup

Jesus is asking the Father if it is possible for him not to have to experience the death and suffering that Jesus knows will soon happen.

# Yet, not as I will, but as you will

"But do not do what I want; instead, do what you want"