Dragged installer into app dock, when I click on it, same old story, this file exists already, do you want to replace it?
Let me take you through this from start to finish, because something just isn't connecting here:
1. Download the Flash Player distribution file from Adobe. It should be called "install_flash_player_osx.dmg"
2. A DMG file is kind of like a virtual disk. That is, when you double-click it, it's like inserting a disc into your CD-ROM drive. So, double-click on it and you should see a new disk on your desktop. The disk should have a red icon and it should be labeled "Flash Player".
3. Double-click the "Flash Player" icon on your desktop, it will open the disc and show you one icon "Install Adobe Flash Player".
4. Double-click "Install Adobe Flash Player" and it should kick off the installation process. Note that it may warn you that "Install Adobe Flash Player is an application downloaded from the Internet. Are you sure you want to open it". If so, be sure to click "Open".
5. Now the installer officially starts - it should look like this:
6. Check the box marked "I have read and agree to the terms of the Flash Player License Agreement" and then click "INSTALL".
7. Next you should see a prompt that says "Install Adobe Flash Player wants to make changes. Type your password to allow this". Enter your account password (which you chose when you set the computer up originally) and then click "OK".
8. If your web browser is open during the install, you'll get a prompt that says "Please close the following application(s) to continue" and it will likely list Firefox. Choose "Force Close All" - you will again be prompted for your account password, enter it and and then choose "RETRY".
9. Now the installation should complete. Once it does, you should eject the "Install Flash Player" virtual disc on your desktop by dragging it to the trash. When this is done, you should be able to use Flash to your heart's content.