Blocked Plug-ins on MacBook Pro?

[Amzo]

so i just got a macbook pro and it's not new, it has been used. so when i try to go on any video websites, it does not work. for example, on youtube, i click on a video and it just comes up saying blocked plug-ins and does not play. It does this for every video. I have searched on the internet multiple times to try and find the solution but i have had no luck. i have tried going on to system preferences, then flash player but flash player is not there. Please try and help. If you have any questions just ask and i will answer them in additional comments or i will comment on your answer. thank you

Please try and answer, this is the second time I have asked this question
So in the small window it says Mac OS X version 10.6.8 Processor: 2.3 GHz Intel Core i5 Memory: 4 GB 1333 MHz DDR3 It also has a button for software update and a button for more info Also my maths is a website for schools to do homework Any help would be appreciated thanks

[Fred]

Go to adobe.com an download flash player. If the machine does not allow it you need to go to the security section and look for the settings for installing. There is an issue with Mac that any non approved software will not load. On recent models this can be tunred off, but after installing if you turn it back on it uninstalls the program.

[SilverTonguedDevil]

The computer is FINE!!! The problem is the OS version. UPGRADE!!!

You have asked this question twice, but you haven't told what you have once. Top menu bar, Apple logo > About This Mac.

EDIT :

Older versions of Adobe Flash plug-in are blocked by Apple, because of security faults. You can install the newest Flash plug-in here: http://get.adobe.com/flashplayer/

As for the school website, it will show requirements for the web browser. Without knowing the URL of the website, I haven't a clue.

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