The proles are free to live their lives how they want to, for the most part. The proles, consisting of nearly 85% of the population, are not part of the party, and are not watched incessantly like party members are, or those that work for the party. Winston envies that freedom. He wants to be able to live his life unexamined, and with whomever doing whatever he wants. He is sick and tired of the constant fear, paranoia, and surveillance. The proles don't have to worry about that, because the party doesn't worry about them. They spend most of their lives struggling to work and make ends meet, and the constant warfare that exists in the world keeps their passions and patriotism afire and satisfied.
Winston wonders why the proles don't rise up and rebel against the party, becuase if they did, they would squash the party instantly from sheer numbers alone. They have, through the fact that they are so large in number, the power to get rid of the thing in life that Winston hates so much: the party. He envies that power. He finds them superior because they have potential, they have freedom, and they have a life that they can live as they choose (in their limited circumstances). I hope that those thoughts helped; good uck!
I believe that the passage you want to look at is towards the end of Part 2, Chapter 7. In this passage, Winston is thinking about the differences between the proles and the Party members.
The most important conclusion that Winston comes to is that the proles have stayed human while the Party members have not. The proles still care about individual relationships and their connections with other people. They have not, as Winston says to himself, become hardened inside. This makes them superior to the Party members because they still have feelings and emotions where the Party members do not.