So there are actually two like buttons. Next to other people's posts on the right hand side is a "+" a dash underneath and then a "-". So it's self explanatory that + is like and - is dislike. There's also a "thanks button on every post on the top of the post next to the multi quote button. That thanks button only shows up after a certain number of posts (I think it's after the topic hits the 3rd page or something). That's basically the same as liking the post 3x.
Unfortunately you cannot do this to your own posts
. You can see how many likes you have on your profile or under your profile picture in every one of your posts. It will be under "Reputation." Yes, you can get negative reputation, which means you get more dislikes than likes.
Just fyi, in case a lot of you guys like doing it lol. I know I do.
Subject: The "Like" button with a bonus "Dislike" button 
February 23rd 2012, 8:08 pm