To install Flash on a 64-bit Linux system, you will need to download the Flash Player plugin from the Adobe website and install it on your system.
Here are the steps to install Flash on a 64-bit Linux system:
Download the Flash Player plugin from the Adobe website:
Go to the Adobe Flash Player download page: https://get.adobe.com/flashplayer/
Under "Step 1", select "Linux 64-bit".
Under "Step 2", click the "Download now" button.
Save the downloaded file to your computer.
Install the Flash Player plugin:
Open a terminal window.
Change to the directory where you saved the downloaded file.
Make the downloaded file executable by running the following command:
chmod +x flash_player_npapi_linux.x86_64.tar.gz.sh
sudo ./flash_player_npapi_linux.x86_64.tar.gz.sh
After installing the Flash Player plugin, you should be able to use it to view Flash content in the Firefox web browser.