From the assignments tab, select the "+Assignment" button in the upper right-hand corner of the page or the "+" button to the right of the name of an assignment group, if you have any. If you selected the "+Assignment" button, you will taken directly to the full assignment editor, and if you select the "+" button, you will be prompted to enter the type, name, due date, and point value of the assignment. You can select "More Options" to access the full assignment editor".
From the assignment editor, you can enter an assignment description, a point value, an assignment group, the format in which grades will be displayed, submission type, whether or not this will be a group assignment, whether or not the assignment will be peer reviewed or undergo moderated grading, and enter a due date.
Follow this tutorial for more detail on how to use the assignment editor.
You can organize your assignments in groups to differentiate between assignment types, order assignments by unit, or to weight grades in your course.
You can use the Modules page to organize your assignments alongside files, discussions, quizzes, or other components of your course.