The first sentence makes no sense at all, a kind of literally translation would be:
I find go the farm...
Auf has several meanings, among them there are:
Some examples of this:
Auf dem Baum (in the tree)
auf der Erde (on earth)
auf dem Hügel (on the hill)
auf einem Pferd sitzen (to sit on/upon a horse)
warst du schon auf der Polizei? (have you already been to the police)
auf Gleis 3 (at platform 3)
auf Jamaika (in Jamaica)
auf dem Bauernhof (at the farm)
auf den Bauernhof (to the farm)
Prepositions in german are usually very difficult when learning. I recommend you to try to remember in which cases you use which preposition, it's a long way but with practice you will get better.
zu to bind the verb, it's kind of the english
Ich muss verstehen was ich lese, um es den anderen zu erklären (I have to understand what I'm reading in order to explain it to the others)