Need Help with a Java Assignment

For school, I need to write a java program that is based on a gradebook. it needs:
-user inputs how many floating point numbers to use (grades)
-use three arrays, one of which will be for strings and the other two will be doubles (the arrays will be student1, student2, assignment, etc)
-load the arrays in parallel (Assignment 1, Student 1's grade for assignment 1, Student 2's grade for assignment 1,etc)
-need a method to calc. avg score
-need a method to calc. letter grade
-allow users to print out the gradebook
-allow users to print out a list of avgs and grades for both students

unfortunately, i have no idea what i'm doing.
can anyone help me?

Show us what ever code you have. No one here is going to do your homework for you.