You bring a CC or a GS major declaration form from your Dean, and the Director of Undergraduate Studies (DUS) will sign it. You should also download and bring a copy of the MESAAS worksheet . The DUS will discuss the program with you and answer any initial questions that you might have.
The name of the faculty member currently serving as DUS is listed here and faculty office hours are listed here. The DUS is your adviser of record within MESAAS, and will expect to see you from time to time in the course of your work.
The worksheet is fundamental. You and the DUS will use it, over time, as a basis for planning your major. When a satisfactory program is agreed on, you and the DUS will fill out a final worksheet (including future courses yet to be taken, which will be so marked) and then both of you will sign and date it. One electronic copy will stay with the DUS and one copy will go to you. If later you need to change your course plans, just discuss the changes with the DUS and fill out a new worksheet. Without a worksheet on file, signed by the DUS, you have no assurance that the courses you have chosen will be approved for your major.
Grades of C- or better are required for all courses counted toward the major.