I've seen this quote in a couple of different places, apparently this is supposed to be from a letter that Che wrote to his father. However I wasn't able to find any credible source on this. Is it true or is it made up?
The first quote is from the Motorcycle Diaries. He really does say that, but he then goes on to talk about how he is preparing his being as a 'sacred' place where the 'reverberations' of new hope can be felt and heard. He is talking about how he is desirous of taking part in a Revolution which would topple the huge injustices he had seen during his travels throughout South America.
I'm having trouble finding a legitimate source for the second quote. I have found contradictory explanations of its context as well. Some claim that it is a letter to Che's father. Others claim that he wrote it down in his diaries. None cite a specific published book or archival source for the quote.
According to the websites that offer at least seem to offer little context, it was written after Che and several other revolutionary soldiers executed Eutimio Guerra. Eutimio had been working with the Batista government as a spy, his betrayal was discovered, and he was summarily executed.
Jon Lee Anderson, who wrote the essential biography of Che, paints a very unflattering picture of Che during this event. He quotes several documents written by Che about the event which are cold and seemingly disconnected with the violence being described (Eutimio was shot in the head). Anderson, however, despite talking about this in a very critical tone and citing several documents does not make mention of the second quote.
I am not certain that the second quote is fake or even sure that perhaps the context offered online is just wrong and that it was written elsewhere. All I know is that I cannot confirm it. Sorry.
Edit: In regards to questions about Che Guevara and whether he was a murderer, a racist, etc., I found a great post from last year about him.