In order to paraphrase a sentence, you need to be able to understand what it says and state the same with your own words.
Bearing that in mind, first, you need to read the sentence and mark any words you don't understand. Once you underlined the words you don't know, you should look up words you don't understand in the dictionary. In this step you should focus not only on understanding the meaning, but you can also look up synonyms that might help you comprehend and paraphrase. After understanding the sentence, you should reread the statement to find the main ideas and details. You need to identify the main ideas to know what's important in the sentence that NEEDS to be present in your paraphrased sentence. Finally, you are ready to simplify the sentence by rewriting it in your own words.