Warning: You should only activate Java on sites you trust.
Activate Java once
When you see the "Activate Java" message, simply click it to load the Java content normally.
If there is no visible area to activate Java content in the webpage or if clicking on the "Activate Java" message doesn't work, look for the plugin icon in the address bar. Click on it and, in the message panel that opens, choose Allow Now to enable Java content temporarily.
Note: The next time you visit the site or any other that uses Java you will see this message again.
Always activate Java for a site
If you have a trusted site that uses Java and you need to use that site often, you can make Java work normally on just that website.
Click the plugin icon in the address bar and a message panel will open.
In the message panel, click Allow and Remember.
Now, whenever you visit this site, the plugin will automatically run and you won't get the "Click to activate" message.
Java security prompts
After activating Java for a site you may see a security prompt, asking you to confirm that you want to run Java, or a message such as "Application Blocked by Security Settings", with no option to run Java. These security prompts and messages come from Java itself, not from Firefox, and depend on the website and your security settings in the Java Control Panel.