How do I know if I have a spyware on my iphone?

It would only be there if you put it there or you jailbroke your iPhone.

Why do you think you might have spyware?

roaminggnome is right. Do you believe that you have spyware for some reason?

"Spyware" is a relative term though. If you indiscriminately install apps that you do not need, and allow them to use your social media accounts or location data then they can "track" you and learn all kinds of things about you. This is the case with any phone or computer that you use of course. The majority of social media users willingly reveal enough data every day through Facebook, Twitter, Instagram, etc. that you could consider all of them spyware.

However, unless you jailbreak your phone, or sideload applications using an untrusted "configuration profile", you cannot possibly have actual spyware or malware on your iPhone (it's not an Android or Windows phone).

my phone has never been jailbroke but I got a message that said call this number and it blocked my internet from working. I did not call the number and the website it referred to was security-alert1.com. When I googled that from a computer it was a scam. How do I keep that from getting on my phone. When I dialed 611 from my phone the message went away. How do I know if my phone is safe.

A popup message does NOT harm your phone. Ignore such messages, and never call any number presented.