There are two ways to propose an amendment for ratification, one via Congress and one through the States.

The Congress:

In Article V of the U.S. Constitution, the Framers established a simple method by which Congress, upon a 2/3s vote of both chambers, could propose an amendment for ratification by 3/4s of the states.

The States:

Step 1 – Two thirds of the states (34) must call for a convention to propose an amendment before Congress sets the time and place for the gathering.

Step 2 – The states must send delegations to the convention to draft and propose the amendment before Congress selects the “mode of ratification” (state legislatures or state conventions).

Step 3 – Three quarters of the states (38) must ratify the amendment.

The text of Article V (convention text highlighted):

The Congress, whenever two thirds of both Houses shall deem it necessary, shall propose Amendments to this Constitution, or, on the Application of the Legislatures of two thirds of the several States, shall call a Convention for proposing Amendments, which, in either Case, shall be valid to all Intents and Purposes, as Part of this Constitution, when ratified by the Legislatures of three fourths of the several States or by Conventions in three fourths thereof, as the one or the other Mode of Ratification may be proposed by the Congress …