Help with my current code to calculate basic arithmetic

I am writing on MASM and need help with my code to calculate basic arithmetic. I am new to assembly language so I am lost on inputting and having a workable code.

Here is the prompt, and my code is available as well. Revisions to be made.

Program Description

Write and test a MASM program to perform the following tasks:

1. Display your name and program title on the output screen.
2. Display instructions for the user.
3. Prompt the user to enter three numbers (A, B, C) in descending order.
4. Calculate and display the sum and differences: (A+B, A-B, A+C, A-C, B+C, B-C, A+B+C).
5. Display a closing message.

Program Requirements

2. The main procedure must be divided into logical sections:
   1. introduction
   2. get the data
   3. calculate the required values
   4. display the results
   5. say goodbye
3. The results of calculations must be stored in named variables before being displayed.