I’m pretty sure there are way better ways to do this, but I was struggeling with the same thing. This is how I got it to work:
I created a definition for the table in the CSS:
border: 2px solid #444444;;
Now when I want a character to say something I use a table like below:
<table class="speech" width="700px">
<td><img src="images/profilePic.jpg" alt="pic" width=100px px/></td>
<td style="text-align:left" width=600px>Maybe we should stop talking about it and start showing it.</td>
Again, I think there must be way simpeler ways to get the same result (or even way better), but this is how I managed to get it to work.