There are two main parts to declaring your major.
1. Choosing your major: Some students know from early on in their college careers what they want to study, either because of strong interests they've developed previously or because of their long-term goals.
Many students come to college not knowing what they will major in, and quite a few change their minds during or after the freshman year. Consider this decision as a process - weighing your interests, gathering information, talking to people - there are a number of resources designed to assist you in thinking through your "major" decision.
2. Officially declaring the major: Your need to apply for acceptance into the major you have chosen and gaining official approval from the appropriate department. You will declare your clusters at the same time as your major. All this involves a series of steps, outlined in the major declaration section of the sophomores website.