1. Remove Your old flash plugin (if You have it)
dnf remove flash-plugin
2. Add rpmfusion repo
http://rpmfusion.org/Configuration
3. Install converter
dnf update
dnf install freshplayerplugin
4. Go to: https://get.adobe.com/flashplayer/otherversions/
[http://get.adobe.com/flashplayer/otherversions/] and chose FP 23.0 for.