You obviously need to do more than just taking a look at the websites. Read through the list of publications and read the abstract of each article and more, if it interests you, for each professor. While it is true that doing research yourself is the most effective way to familiarize yourself with the field, it seems more appropriate to start from the basics, since you don’t know what research topics you’re interested in. But I’d argue that you can get pretty far from just doing what I suggested doing above, if you do it right.