Check that you don't have something like
p {
...
text-align: left;
...
}
in your css, since that will override the attribute in the div.
To fix the width, do something like:
p.caption {
font-family: "Arial", sans-serif;
line-height: 1em;
font-size: 0.68em;
margin: 0.3em 15%;
}
.img {
width: 70%
}
with <img src="images/2_06.jpg" class="img" alt="2_06.jpg" />