From your question, I'm not sure if you are asking about the plot, character, or theme. Since the other responses focused primarily on theme, perhaps you might want more on plot. Of course, the e-notes plot summaries are excellent for this type of information.
But, I'd like to give you my take on Arthur Miller's Death of a Salesman. The play begins with a domestic scene--a tired man coming home from an unproductive day at work. His loving wife attempts to console him and reassure him. Willy's sons are also home, and what should be a happy scene becomes tense as Willy vacillates in his views of Biff, calling him a prince one minute and a lazy bum the next. Biff's views of his father are also complex, and he is contemptuous of his father's mumblings and suicide attempts. As Happy and Biff reminisce about old times and share their feelings about the present, we soon learn that Happy is a flagrant philanderer and Biff is a drifter. Both think they are capable of much more.
So, with this setting, Miller shows us the past. We gain an understanding of the past through Willy's flashbacks. As much as Willy would like to suppress these memories, they continually emerge to haunt him. We see such flashbacks as Willy's focus on the young Biff and his neglect of Happy; Ben's visit to the family, full of bravado and intimidation; the young Biff treating the girls rough and stealing; and finally Willy's infidelity that Biff uncovered.
So we see clearly how the past affects the present family situation. And yet, we see how the family clings to those same beliefs and values that caused the problems in the first place. Willy cannot let go of the fact that Biff will be the success that he himself had been unable to be. And Biff has a difficult time untangling himself from this expectation of him as well. Happy feeds into it by suggesting a proposition that deep down each probably knows will fail: the Loman brothers' sports-line, to be financed by a man Biff briefly worked for and stole from. We learn that the Lomans are still chasing pipe dreams and are each failing miserably. Willy is fired from his job, Biff is brushed off by his old boss, Happy is stuck in a low-level management job, not likely to advance.
So, much of the play is uncovering why the Lomans are dysfunctional, how the past affects the present, how unrealistic expectations can lead to disillusionment, and how illusions about self, family, society can converge to create failure on multiple levels.
In my mind, the play centers on the crushing brutality of certain dreams. The notions of success and achievement that are forced on many in their pursuit of "the American Dream" is one that has to be analysed and reconfigured. This standard vision places a primacy on financial success and monetary acquisition that there might be a loss of focus on what is important. While others pursue it to a zealous degree, keeping pace with others in some random sprint, Miller might be suggesting that this entire frame of reference needs to be evaluated. Wily is crushed under the weight of the American Dream. Through his character, others can recognize their own pursuits and sustain examination in seeing if they are worthwhile endeavors, steeped in a reverence of what is important and relevant.
In the play 'Death of a Salesman' by Arthur Miller, Willy Loman comes across as a well-meaning dreamer who expects to achieve the American Dream (self-sufficiency,owning his own land,a prosperous old age,respect) without doing anything out of the ordinary. My take on hime is that he has low self-esteem - the esteem he had when sales were high was not down to himself and his efforts, he just benefitted from a reasonable economy and the market back then being strong for his goods. He was riding a wave not of his own making. Many people did go on to achieve the American Dream - but there was one difference in what they were prepared to do and that was - Risk! This is a hard one for all of us - like us, Willy is caught between taking a chance that goes wrong and losing everything or sticking with the mundane grey status quo. He finds a unique way out!
Willy Loman is the typical American man searching for the American Dream in the form of retribution for all the hard work he DID put in as a salesman at the height of his "glory". His "death" came long before his physical death. It came out of the rupture of his relationship with Biff, and afterwards it influenced everything else.
In the end, his death meant the resurgence of his family which puts into perspective the possibility that it would have been that way from the get go. Such is the absorption of Willy's life.
My pont of view of what is happening in Arthur Miller's play Death of a Salesman is that we are given an intimate and compelling character study of a particular man of advancing years, Willy Loman. As mkcapen1 notes, this one man can be seen as a sort of late career, working "everyman."
Willy's struggles can be understood through any number of terms and models, but I find the psychosocial theories of Erik Erikson to be helpful in understanding some of the main conflicts and symbols in the play. In the terms of Erikson's famous theory, Willie is in either of the two final stages, Stage 7 (Generativity versus stagnation) or Stage 8 (Ego integrity versus despair). Focusing on Stage 7 gives me a way to make sense of Willie's obsession with planting seeds. Focusing on Stage 8 allows me to make sense of his fear of losing self-sufficiency and status and his thoughts (and perhaps act) of suicide.
The point of view of "The Death of a Salesman" is that Willy Lowman represents the everyday man who had bought in to the American Dream. He wants a home of his own and his family to have benefited from his work. He also wants his life's work to have meant that he progressed to have a comfortable life towards the end of his years.
However, the life that Willy Lowman is now living is one of shattered dreams. He can not pay his bills as sales are down to nothing. He is having to get a weekly draw to survive and is failing in the company. He has become suicidal.
In the end Willy Takes his own life so that his family can own the home that he can could lose if he stays alive. He has given them the American Dream through his death.