If you haven't joined any LinkedIn Groups yet, why not make the Thanksgiving break a time to get started?
Groups are collections of people who share something in common--well, duh. On LinkedIn, groups are where conversations take place, and where you can keep your ear to the ground about the industry of your choice (writing, editing, English-y sorts of things). You can also jump into that conversation and begin establishing yourself as an insider.
They are not like Facebook's system of "liking" an organization and then waiting for them to send you a coupon or something. (I've never really gotten the whole Facebook "like" thing--what if I want to "not like"? or discuss?)
You'll find the official LinkedIn FAQ information here: http://help.linkedin.com/app/answers/detail/a_id/1164. Before you start a group (the first major set of topics), take some time to be a member (the cluster of topics near the end of the article).
On the etiquette and uses of groups, here's a great article about making the most of your group experience: http://socialmediatoday.com/stephaniesammons/1945416/how-make-most-linkedin-groups