I am not getting the problem statements which we are facing currently.
I don't understand what you mean.
Are you responsible for writing a report all about six sigma? If so, just start writing. Write about what one journal article says, then another, and then another.
Write several paragraphs, and do not worry about if they flow together well.
After you have written several paragraphs, go back and write an intro that gives a thoughtful THESIS STATEMENT which will be the theme for the report.
But do not worry about that right now. For now, just write one sentence about six sigma, and then explain that sentence with a few more. That'll be one of the body paragraph. Does this help?