Settings > General > About > Version
If your version is iOS 9.3.5. – you’re good to go! If not, you need to update. The good news is that it is easy to install an update. Apple gives options on installing updates, and they are all simple and straightforward. Just go to their instructions if you are not sure how to do it.
Also, before you click on any email or text message on your phone – make sure it’s coming from a reliable source. If you are not sure, just don’t click !