Article V of the U.S. Constitution outlines the methods for amending the Constitution. Here is the information filled in based on your prompts:
1st Method - need two-thirds [fraction] of Congress to PROPOSE an Amendment. 2nd Method - need two-thirds [fraction] of the state legislatures to ask Congress for a national convention to propose an Amendment (this method has never been used). Need three-fourths of all states to ratify or APPROVE an Amendment. This is done by state legislatures or a special ratifying convention. Over 11,000 proposed Amendments since the early 1800s. Only 27 have been ratified. The 1st Ten Amendments were a package deal, and Amendments 18 [Prohibition] and 21 [Repeal of Prohibition] cancel each other out, leaving 15 separate Amendments that went through the process.