At the Top Row Toolbar of the Kindle Fire:
Swipe down to get Settings / More / Device / and then CHECK the box that says: Allow Installation of Applications from unknown sources
Download Dolphin Browser APK
Launch ES File Explorer, and look in the Downloads folder. You'll see the Dolphin icon...tap it to install.
Download Flash api
Launch ES File Explorer, and look in the Downloads folder. Install Flash apk.
Use the Dolphin browser instead of Silk to access Flash sites. That should do it. Dolphin has some other settings you can tweak later.