where can I find a free, easy to understand online English grammar lessons?

nesty, there are scads of them. Let me hit my bookmarks and give you a few links.

http://owl.english.purdue.edu/

http://bcs.bedfordstmartins.com/writersref6e/Player/Pages/Main.aspx

http://www.grammarboard.com/ipb/index.php?

http://andromeda.rutgers.edu/~jlynch/Writing/

These aren’t necessarily the best, but I bookmarked them because they had a good explanation of something I looked up.

BTW, AbsoluteWrite has a grammar board where knowledgeable people will answer specific grammar questions that arise.

Well, it’s not free but it is very inexpensive and worth the money! Try http://vu.org They have a lot of other classes/courses. Check it out, at least. I’ve enrolled at vu.org several times and the knowledge I gained from there has been useful in getting a job. People there are very nice and helpful.