Why can't I use text features like invisible ink

Those are features of iOS 10 which will be released on the 13th. You can update then and get those feature.

http://www.apple.com/ios/ios-10/

If you decide to update on release date, the Apple servers could be very busy, so be very patient if you can't update right away.

updated phone and cant send invisible text messages. I press and hold send button after I typed in text and nothing happens

Did you try Settings>General>Accessibilty>Reduce Motion>Off.