What parts of the constitution discuss the eastlishment and duties of the three branches?

Article i,ii and iii 

the first article of the constitution introduces the legislative arm of government - the congress of the united states, consisting of the house of representatives and the senate. the second article describes the presidency - how to select, vow, the privileges and responsibilities of the president. it also introduces the office of vice-president, who takes office after the death, resignation or incapacitation of president .article third describes the judiciary, including the supreme court. besides the supreme court, congress may establish lower-level courts, where judges and judgments are subject to the supreme court, the article enacts jury, introduces the concept of betrayal, and gives congress the right (with limitations) to establish punishment for it.