If you're using Chrome, it will probably appear a message bar like this:
So first enable Java execution by clicking "Run this time" or "Always run on this site" button. After that just click the Test button below to see what JRE versions your browser can see in your PC.The method for getting it is the one provided by Java Deployment Toolkit Script. If you got more than one version, sometimes Chrome won't correctly see them all, as explained in this post.
After testing it with Chrome, go ahead and test it with other browsers. Below is the code of this test page: