First, please be aware that there is no single “official” answer to this question. Different historians can define the phases of the movement differently. You may want to consult your text and/or the notes given by your instructor to see what the right answer for your particular course is. That said, we can generally say that the Civil Rights Movement went through three main phases in the time after World War II.
The first of these phases was the phase in which it used the court system in an attempt to gain rights for African Americans. This phase started very soon after WWII. In this phase, activists focused mainly on using law suits to force the desegregation of schools in the South. The major victory for this phase of the movement was the 1954 case of Brown v. Board of Education.
In late 1955, the Montgomery Bus Boycott began. This marked the beginning of the second phase of the Civil Rights Movement. (Please note, though, that this does not mean that the movement stopped using law suits altogether.) This was the phase in which activists used direct action to try to promote integration and black rights. This phase included the bus boycott, the sit-ins at lunch counters, the Freedom Riders, the march from Selma to Montgomery, and many other of the most iconic moments of the movement. This was the phase dominated by Dr. Martin Luther King, Jr. Its greatest victory was the Civil Rights Act of 1964 (or perhaps the Voting Rights Act of 1965).
As the movement continued, however, some African Americans became disillusioned with the ideas of nonviolence and integration. This led to the third phase of the movement. In this phase, more radical black leaders came to the fore. They were less willing to work with whites. They were also less interested in rights and integration and more interested in black nationalism. This phase of the movement was characterized by leaders such as Malcolm X and the Black Panthers. It did not have any specific events that can be pointed to as victories.
In this way, the Civil Rights Movement changed over time. However, we should be sure to remember that these phases did not occur at completely separate times. Instead, they overlapped to a considerable degree.