References to Gatbsy in the first two chapters come in conversation and in Nick's narrative.
Gatsby is initially mentioned in the opening section of the novel, which acts as a preface:
"Gatsby who represented everything for which I have unaffected scorn."
"No - Gatsby turned out alright in the end."
In this section, we see that Nick's introduction to the story is also his introduction of the reader to Gatsby. It's worth noting that here the dynamic and complex views Nick ultimately takes regarding Gatsby are rather fully represented, the good, the bad, and the fullness of his grandeur.
The next mention of Gatsby comes from Nick's description of his own living situation, effectively in the shadow of Gatsby's mansion. Gatsby is clearly extremely wealthy.
Jordan next brings up Gatsby's name when she learns that Nick lives in West Egg, implying that Nick must know Gatsby because everyone, she presumes, in West Egg knows Gatsby. He's too big of a figure not to be known by all. When Nick tries to explain to Jordan that Gatsby is his neighbor, Jordan tells him to be quiet because she wants to hear Daisy and Tom's fight. This implies that Jordan's interest in Gatsby is limited (and probably superficial).
At the end of the first chapter, Nick sees Gatsby in a romantic posture, yearning for the stars with outstretched arms on his balcony.
In the second chapter, in the city with Tom, Myrtle, and Myrtle's sister and husband, Gatsby's name is brought up in connection with his parties. There is talk of Gatsby being somewhat dangerous.
"Well, they say he's a cousin of Kaiser Wilhelm's. That's where his money comes from."
"I'm scared of him. I'd hate to have him get anything on me."
Through all of these references we see that Gatsby is an emminent figure whose name precedes him. His reputation is varied and an air of importance and of mystery hangs upon his name.