Here are some sites that may have what you need.
Here is a webpage I used to print up for students to use when discussing how to paraphrase:
(Broken Link Removed)
Don't let the "plagiarism" label on this scare you away! Yes, it's about plagiarism, but it's mostly about how NOT to plagiarize -- by learning how to paraphrase and quote correctly.
Look under Some More Examples. First you'll see an original paragraph and the source of it. Then you'll see Versions A, B, C, and D -- attempts to paraphrase correctly. You'll see that A, B, and C are not done correctly (and explanations why), and you'll see that D is done correctly (and the explanation why).
Here are further sources you may find helpful:
What concept? What kind of help?
Paraphrasing in general just involves saying something in a different and (usually) briefer way that is easier to understand that the original. You have to use your own words and judgement about how to do that.
Sometimes it is done to avoid plagiarism in term papers etc., when using material from other sources without attribution. This is risky and not recommended. It is better to credit and reference your sources.
You will find quite a few links online by Googling "paraphrase worksheets". I did not find any of them useful. Some were from the U of Phoenix and many described courses or texts that were not free.