removing name on circles but having appear when mouse over

Do you have a Custom CSS plugin?

have only the image and not a title when first appears but would like the title to appear when mouse over.

Install this Custom CSS Manager plugin http://wordpress.org/plugins/custom-css-manager-plugin

Then use its “CSS Code” section of the dashboard to hold your CSS modifications:

.hentry .thumbnail-title {
    left: -9999em;
}

.hentry a:focus .thumbnail-title,
.hentry a:hover .thumbnail-title {
    left: 50%;
}