OK, I then i'm going to be honest and say since you're using HTML only I'm not much of a Javascript master and that's what you're goin to need. You're also going to need to force the refresh of the page for these things to update. What you'd need to do is on th PageLoad event request the System's time and if that time is equal to a certain value then display a certain image and certain show information. And you can convert their time to a GMT time so don't worry abou that,
Code:
var tNow = new Date();
GlobalT = tNow.toGMTString();
if(GlobalT.getHours() == 19)
{
//set something yourJPEG in here or your information.
}
Now believe me, it's not going to be that simple but it'll get you on the right track.
see this site
Boog's