Firefox 4 Browser.....?

I had the Firefox 3 and decided to upgrade to Firefox 4, doing so I lost the automatic spell check...That I need so did a System Restore to go back the previous Firefox Browser setup. My PC is setup by clicking the Firefox Icon my Internet & Homepage comes up. Unfortunately after the System Restore I've lost that Ability.. By clicking the Start Tab I can click on the Internet Explorer Icon to get the Internet though....I do like the Automatic Spell Check feature with Firefox though, I'm Computer Illiterate just need some help at clicking the right tab or icons and taking the right prompts. Thanks