There are so many online writing courses these days that it's sometimes hard to decide which class to take.  Here are a few of my favorite places that offer dynamite classes (and the prices are right, too!) If you have an email address, you can take these courses.   

RWA Kiss of Death Chapter COFFIN (College of Felony and Intrigue) - Offers courses on writing craft and technical aspects of criminal behavior and law enforcement. You don't have to be a member of RWA or this chapter to participate in these classes.

Writers Online Classes - primarily on the craft of writing. Open to all.

Earthly Charms Workshops - offers 2-week and 4-week classes. Open to all.

Other good sites to help you learn how to write are Writers' Village University and InspiredAuthor.  Join WVU and get free access to over 200 courses. InspiredAuthor offers free articles, a free live chat every Friday, and paid courses through their online school.