please help I'm a beginner programmer and I need help with this java program. Please use the Eclipse IDLE because that's what I'm working on and also explain step by step. And follow the instructions provided.

Programming Exercise Chapter 4 - #3 Test Scores Use JOptionPane for I/O. Use constants where appropriate. You should have a TestScores.java and a testing class that houses your main. For the Coding Style aspect of your homework, I'm looking at the following. Use of constants. Try not to hard code numbers and strings into your source code. Use finals. WRONG: newValue = oldValue *(1+.08); RIGHT: final double INTEREST RATE = .08; newValue = oldValue *(1+INTEREST_RATE); 3. TestScores Class Design a TestScores class that has fields to hold three test scores. (If you have already written the Test Scores class for Programming Challenge 8 of Chapter 39, you can modify it.) The class constructor should accept three test scores as arguments and assign these arguments to the test score fields. The class should also have accessor methods for the test score fields, a method that returns the average of the test scores, and a method that returns the letter grade that is assigned for the test score average. Use the grading scheme in the following table: Test Score Average Letter Grade 90-100 A 80-89 B 7079 60-69 D Below 60