How to write something which is already written?
Do not try to rearrange or paraphrase, but write in your own words.

How do you do it:


Read what you need to read.
Think about it.
Write it down again (without looking at the original source). 


It takes more time than paraphrasing/rearranging, but it is worth the effort. You see if you really understood the topic and also you may discover that you have something new to say.