How much education do you need to become a Marketing Major?

As far as I can tell you, you'll need a high school diploma. Given your criteria is simply "Marketing Major", I assume you're asking how to study Marketing in College.

I studied Marketing and Entrepreneurship (dual major) at a large university in Boston (ended up in Finance anyway). You will need a decent GPA, a solid SAT score and you'll need to be able to demonstrate that you've pursued extracurricular interests (sports, instruments... you know the drill) and helped out in your community (ie. volunteering, etc.). An internship at an Ad agency or similar will definitely go a long way. If you can also talk about interesting Marketing campaigns that you've noticed and make observations about them in your application essays, I see no reason why you shouldn't be able to score a place in a Marketing program at a school that reflects your engagement level, and is within your range for SAT scores and grades.

Given that you are already here, asking the right questions, I'm sure you're well ahead on the right track. Good luck!

Managerial Communications: This course provides instruction in organization and construction of the written, technological, and oral communication used in modern business.
Macroeconomics: Students will examine the fundamental analytical structure of a macro economy and become familiarized with the problems of employment, inflation, interest rates and business cycles.
Principles of Marketing: This course examines the basic marketing principles practiced by modern organizations including product development, distribution, promotion and pricing.
Principles of Management: Students will be introduced to the principles of management examining their application in public and private, profit and non-profit organizations.
Principles of Finance: This course examines the role of finance in relation to other business operations and within the financial community.
Principles of International Business: This course familiarizes students with the multidimensional macro-environment of international business and teaches them the tools necessary for the analysis and evaluation of diverse problems within that environment.
Business to Business Marketing: This course will include an overview of raw materials suppliers, manufacturers and middlemen as well as the basics of industrial demand, marketing intelligence systems and analysis, product and service best practices.
Marketing Research: Students will learn basic statistical analysis of research findings and about the various tools and techniques used by managers of marketing research.
Consumer Behavior: This course will discuss best practices and practical marketing applications with a customer focus. It will also analyzes motivation, personality and perception, learning, attitude formation, and the importance of group dynamics, social class and culture on behavior in the marketplace.
Master of Business Administration (MBA) and Master’s Degree Programs
Both an MBA with a concentration in marketing and a marketing master’s degree will prepare you for marketing leadership positions across any number of business industries. While each track offers advanced training in marketing and managerial concepts and practices, they each have a distinct objective:
A marketing MBA trains you to develop a broad set of business skills that you will be able to apply and transfer to other business arenas.
The highly specialized marketing master’s takes a less general path by offering students the opportunity to focus almost exclusively on marketing-related issues.
Your marketing MBA or master’s in marketing will be instrumental in helping you achieve a position of leadership in your career. Many people with these advanced degrees become market research analysts, sales/territory managers, public relations managers, advertising managers and product managers.