Go to Google.com or a similar search engine and type in the name or author of the book you wish to read, whether it be Herman Melville, Mark Twain, Edgar Allan Poe, Washington Irving, Jack London, Edith Wharton, Henry James or other American authors. If you don't have a particular book in mind, go to americanliterature.com, literaturepage.com, readbookonline.net or a similar page. They hold huge repositories of classic works of literature, allowing you to search for specific titles or browse their libraries as you wish.
Scan the results of the search for the complete text of the book you want. The description in the search engine should contain words such as "etext," "transcript," "complete text" or the like. If you are using a site of collections such as americanliterature.com, click on the name of the book you wish to view, which should bring up a copy of the book for you to read.
Analyze the format your chosen website has used to display the book. In many cases, the electronic text is divided by chapters, which you can click on to jump straight to the pertinent passage in the book. Other times, the text may be presented in a single long sheet.
Check the site to see if you can adjust the size and font of the text to your liking. Some sites offer controls that permit this, letting you read the text in a manner that is comfortable for your eyes.