I have to write 4 paragraphs about my interpretation of each of the themes in the book. I already had one paragraph defining what a utopian and distopian society is for that theme. Please help. Anything will be greatly appreciated.
As far as the dependence on technology goes, think about what Millie's life is like. She totally depends on the parlor walls to give her any semblance of a personal life.
You could also look at things like the mechanical hound. This is a society that doesn't even use real people for tracking down and killing others. Instead, they've created a machine for that.
So you have a society that is so completely divorced from humanity that people need technology in place of relationships (love) and technology in place of violence and execution (you could call this hate). If you have machines in place of love and hate, you're pretty dependent on machines.
Defining utopian and dystopian societies is a good start. You and your reader need to be familiar with each in order to develop, in your case, and understand (in theirs) an effective paper on the topic.
Fahrenheit is considered a book about a dystopian society primarily due to the existence of serious restrictions. For instance, something we as a society currently consider little more than a privilege or necessity becomes an issue of basic human rights in Fahrenheit. This hearkens back to the historical example of book banning and censorship. The burning of books in the novel directly affects the First Amendment in American culture. Firefighters, normally viewed as heroes in our civilized society, become fire-starters, heroes in an entirely different manner to the savage nature of Fahrenheit's society.
Knowledge becomes a caution in Fahrenheit 451, especially knowledge which is gained on one's own steam. Montag realizes that the process of book-burning and knowledge restriction can be considered dystopian.
On the other hand, the concept of a society in which no evil is ever known or promoted, as was the suggestion with Fahrenheit, is commonly considered utopian, at least in literature. Ignorance is bliss is an idiom which comes to mind, and one which seems to provide much of the foundation for the government of Fahrenheit. The idea of it as a utopia is basically this: if no one knows about all those things they censor by burning books, then clearly they don't exist, and therefore the world becomes "perfect."
Obviously this isn't the case, especially with the horrifying imagery Bradbury uses to explain the situation, but that is part of the thrill of it--realizing that no matter how well-intentioned a society might be in censoring material, it alludes to our less-enlightened days of savage human ignorance.