Read this Charles Feng's "AP Macroeconomics Study Guide", which provides a brief outline for the study of macroeconomics and will help prepare you for economics exams. This study guide covers most of the topics presented in this course.
Read this second set of lecture notes from Veronica Guerrieri, which will provide an introduction to the scope and major topics covered by a course in macroeconomics. This reading represents an outline of the course and adds context. You will gain a solid foundation on which the upcoming units build. For instance, the course will refer numerous times to the four components of the expenditure approach - consumption, investment, government, and net exports - and will elaborate on their causes and consequences, what variables alter them, and what effects they have on aggregate demand, aggregate supply, GDP, and so forth.