What are the three parts of the Declaration of Independence?

The first two paragraphs of the Declaration of Independence lay out the underlying philosophy of the role of government and its duty to protect the rights of all its citizens. After an opening sentence stating that it is the obligation of every revolutionary cause to state their reasons and intentions to the world, the Declaration lays out its creed. This section is heavily influenced by the ideals of certain Enlightenment thinkers, namely, John Locke and Jean-Jacques Rousseau. This part contains what are perhaps the most famous lines of the Declaration,

We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty, and the pursuit of Happiness.

If a government will not protect these rights, the Declaration goes on to state, then it should be replaced with a government that will.
The following portion of the Declaration of Independence is a long list of grievances. The Declaration lists twenty-seven different ways that the English King has acted as a tyrant. He is therefore unfit to govern a nation of free people. These grievances are intended to let England, the colonists, and the rest of the world know exactly why the colonies are rebelling. It ends by stating that they have appealed to their fellow Englishmen across the Atlantic but found no aid or sympathy from them.
The text of the Declaration of Independence ends when it asserts the right of the former Thirteen Colonies to separate from Great Britain and form an independent country. The text then mentions the basic powers of a free country, such as the ability to wage war and make alliances, and the text ends with a pledge of resolve and honor from the fifty-six delegates who signed the document.
https://www.ushistory.org/declaration/document/