SQL Challenge: Gradebook

Can someone please help me with this code? I have no idea where I'm going wrong! Below is the goal I'm supposed to be reaching.

"Now, this step is a little tricky. The goal is a table that shows how many students have earned which letter_grade. You can output the letter_grade by using CASE with the number_grade column, outputting 'A' for grades > 90, 'B' for grades > 80, 'C' for grades > 70, and 'F' otherwise. Then you can use COUNT with GROUP BY to show the number of students with each of those grades."

Here is what was provided and the part in bold is my code. It keeps saying I have a syntax error, but I have no idea how to fix it. I'm very very new to SQL. Can someone please help?

CREATE TABLE student_grades (
id INTEGER PRIMARY KEY AUTOINCREMENT,
name TEXT,
number_grade INTEGER,
fraction_completed REAL);

INSERT INTO student_grades (name, number_grade, fraction_completed)
VALUES ("Winston", 90, 0.805);
INSERT INTO student_grades (name, number_grade, fraction_completed)
VALUES ("Winnefer", 95, 0.901);
INSERT INTO student_grades (name, number_grade, fraction_completed)
VALUES ("Winsteen", 85, 0.906);
INSERT INTO student_grades (name, number_grade, fraction_completed)
VALUES ("Wincifer", 66, 0.7054);
INSERT INTO student_grades (name, number_grade, fraction_completed)
VALUES ("Winster", 76, 0.5013);
INSERT INTO student_grades (name, number_grade, fraction_completed)
VALUES ("Winstonia", 82, 0.9045);

SELECT name, number_grade
CASE
WHEN number_grade > 90 THEN "A"
WHEN number_grade > 80 THEN "B"
WHEN number_grade > 70 THEN "C"
Else "F"
END as letter_grade

FROM student_grades;