First - you should have started a new topic - this topic is for reference.
You say you are a beginner but you are trying to do a not-beginner's program so how much experience have you?
Have you been on a COBOL course? If you have then you take the sample code from this topic, study it, and bit by bit make the changes that you require.
If you have not studied COBOL then I would suggest you start by going on a course or get a reasonable book - 'COBOL for Dummies' is reasonable for starters - and do the exercises. When you have finished you should be competent enough to do the program changes you need to carry out the task described.
When you come up against problems at this point then ask your questions on the forum. We will not teach you COBOL but we will help you to overcome specific problems.
The problem I have is that people can explain things quickly but I can only comprehend slowly.