Not able to install flash player on my Macbook late 2008

I tried to installed flash player following all procedure on the trobleshoot but nothing work. What could it be?

MacBook (13-inch, Aluminum, Late 2008)

OS: El Capitan OS X 10.11.14

  Model Name:                         MacBook

  Model Identifier:                   MacBook5,1

  Processor Name:                Intel Core 2 Duo

  Processor Speed:               2 GHz

  Number of Processors:       1

  Total Number of Cores:       2

  L2 Cache:                            3 MB

  Memory:                              8 GB

  Bus Speed:                         1.07 GHz

  Boot ROM Version:             MB51.007D.B03

  SMC Version (system):       1.32f8

  Serial Number (system):     W8907DUL1AQ

  Hardware UUID:                  F56D87EE-7C2D-5086-BEDE-0B13028B675B

  Sudden Motion Sensor:

    State:            Enabled

this is my machine bios.

  Mod

Model Name: MacBook

  Model Identifier: MacBo