The first two paragraphs of this excellent and thought provoking essay serve to establish the context of the narrative of the shooting of the elephant, point towards the conflicted feelings that Orwell feels as a colonial officer, and lastly, indicates the message of the entire essay. In many ways, they are the most important parts of the entire essay - the actual story of shooting the elephant just proves what Orwell has already stated.
In these paragraphs, on the one hand, Orwell had decided that he "was all for the Burmese and all against their oppressors, the British." Yet, on the other hand, he talks of his "rage against the evil-spirited little beasts who tried to make my job impossible" and he dreams of the joy of bayoneting a Buddhist priest. Clearly this irony points towards some conflicted feelings and the cultural conflicts of colonialism.
The second paragraph tells us what Orwell learnt from the elephant narrative and thus points towards the message of the essay:
One day something happened which in a roundabout way was enlightening. It was a tiny incident in itself, but it gave me a better glimpse than I had had before of the real nature of imperialism - the real motives for which despotic governments act.
It is these "real motives" that are explored through the rest of the essay and the way that the actual power and position that white men assume destroys their own "freedom" and converts them into "absurd puppets" who are "pushed to and fro by the will of those yellow faces behind."
Thus the first two paragraphs are crucial for establishing the setting, establishing the conflicted loyalties of the narrator and pointing towards the overarching message of this essay.