It says I have 13 viruses how do I get ride of them

First, take a deep breath.

Second, realize that you don't. That d of attacwhat you're looking at is 100% a scam attempt by a malicious user trying to trick you into either installing their malware, or holding your data ransom.

Chances are this message popped up when you visited some web site or other. That because this kind of attack is most often perpetrated via malicious ads inserted on the page.

Close the web page in question and move on. You can't do much to stop the ads/popups. Just be vigilant.

Scam messages. A non-jailbroken phone cannot get a virus.

Because an iPhone is very secure against any virus or malware.