When you come on, there will be an option from the home page to view unread messages since your last visit. Because there are so many posts, this can get unwieldly, especially is you miss a few days.[
Also, on the bottom of the page is a binocular icon which will shoot you an e-mail when that topic is posted to. You can also use the bookmark feature which will save the topic in your profile, and retrieved from the blue links on the top of the page.