To apply for Master's Program you will need to apply to the Graduate School. Unlike applying for undergraduate admission, applying to graduate school is individualized - each department decides who they will admit. These programs are very competitive. Some programs offers financial aid. You will want to begin with:
Next you will want to go straight to your department for information about applying, and special requiements. Some programs require the GRE and some do not. You must follow the instructions for each individual department.
Finally, you will want to explore cost and funding opportunities.
If you have questions about your program of study it is best to contact the department directly.