Automatically save what you typed in firefox

you need following step for this

With a Firefox extension called Textarea Cache, 
 
you can automatically save what you type in a comment box or Web form and retrieve it, even if your browser crashes. Here's how:

Step 1: Install the Firefox extension, Textarea Cache.

Step 2: Fill out a blog comment or post to a forum.

Step 3: To retrieve your text, go to your Firefox add-ons by hitting CTRL+SHIFT+A, then click on the "Options" button under Textarea Cache.

(Credit: Screenshot by Ed Rhee)

Step 4: Click on the "Open cache window" button.

(Credit: Screenshot by Ed Rhee)

Step 5: Review the text that was automatically saved and copy the text, remove it, or empty out the entire cache.

(Credit: Screenshot by Ed Rhee)

Step 6: To get quicker access to the Textarea cache window, hit CTRL+/ to display the Firefox add-on bar, then click on the Textarea icon in the lower right-hand corner.

(Credit: Screenshot by Ed Rhee)

That's it. Now you can automatically save the text you type over the Web. If you're concerned about Textarea Cache saving credit card numbers or passwords, worry not. The extension only saves text from large textarea boxes, not from small field boxes. Also, the cache is saved locally. Mozilla has reviewed the extension itself and given it its seal of approval