Karen, what word processing software do you have on your Mac? I'm not hugely familiar with the OS, but I do believe there's a Microsoft Office suite for Mac, which would include Word. Not a perfect program, but it works well enough for me. Here also are two Mac-oriented grammar and spell-check programs (though I don't believe they're entirely free):
http://linguisoft.com/
http://mac.softpedia.com/get/Word-Processing/Grammatica-Spelling-and-Grammar-Checker.shtml
Hope that helps!
http://linguisoft.com/
http://mac.softpedia.com/get/Word-Processing/Grammatica-Spelling-and-Grammar-Checker.shtml
Hope that helps!