Open Mozilla and go to Help then About Plugins. That will tell you what is installed, if anything. There is a link at the top kind of on the left on mine, I use 1.5, click on it then on that page click the word "Linux" in the top portion. Do not click the one under Documentation, yet. You should get a page that will tell you what is working and a link to where to download the program. Scroll down the page to see them all.
If you need to you can go back and click the Documentation link. To link a file it is usually something like this.
ln -s /path/to/original/file /path/to/where/you/want/the/link
The link usually goes into /usr/lib/mozilla/plugins. The mozilla may also have a version number sometimes. You will need to check to make sure.
Post back if you have trouble. Take it one step at a time and it will not seem so hard. I have installed Gentoo. It looks impossable, till you just take it one step at a time. Then it is