You can find Chief Justice Taney's opinion here.

The case you're referring to is stylized Scott v. Sanford, 60 U.S. 393 (1857). The names are the names of the parties, and the numbers give the number of the volume of the U.S. Reports that contains the decision ("60"), and the page on which the opinion begins ("393").

The Supreme Court tradition, established by 1857, was for decided cases to be accompanied by a written "opinion of the Court," with one judge speaking for the Court in the form of a "majority opinion." (Sidenote: this was a uniquely American format, adopted by Chief Justice Marshall during his term. Prior to his tenure, the Supreme Court issued opinions from each judge!) Where a justice reaches the same outcome as the majority, but for different reasons, he supplies a "concurring opinion." Where a justice reaches a different outcome, he supplies a "dissenting" opinion. For more on early Supreme Court practice and Chief Justice Marshall's reforms to the Court, see Gordon Wood's Empire of Liberty, or, if you have access to a law library, Hart & Wechsler's seminal The Federal Courts and the Federal System.

All of this is to explain that the "official document" you're looking for is the Court's "opinion." Any quotes from specific people would come from the Justices themselves. Another commenter linked to one version of the opinion, but another version can be found on Google Scholar here.

In Dred Scott, Marshall's reforms notwithstanding, every justice wrote an opinion: the majority opinion, six concurrences, and two dissents. If you want a significant "quote," you would have to look to the majority opinion. I leave that task to you: there are a lot of quotable and significant moments in Taney's majority opinion.