If you do not have the spell check function on your Fire Fox browser, it is easy to add, just
1. Open Firefox, then type about:config in the address bar and hit Enter.
2. In the Filter box, type spellcheck.
3. Right-click layout.spellcheckDefault, and then click Modify. Raise the value from 1 to 2.
4. Restart Firefox.
You now have a spellchecker.