Open Adept Manager by going to → → .
When prompted to enter a password, enter your user password and press OK.
Locate the Search box just under the toolbar at the top of
the window and type flashplugin
.
Locate the package named flashplugin-nonfree and select it. Press the Request Install button.
Locate the the Apply Changes button in the top toolbar and press it.
After the installation is complete close the Adept Manager.