Center All Content in table cells

I have no experience in css. I would like to format all my tables to be centered. Here is a link to my table and below is my css custom code.

http://careerintro.com/career-fairs/

.tablepress thead th {
font-family: Tahoma;
font-size: 14px;
color: #ffffff;
}

.tablepress thead th,
.tablepress tfoot th {
background-color: #ff0000;
}

http://wordpress.org/plugins/tablepress/