I am currently using a classes to position the headings for my repeater.When I run the page the item doesn't stay with the content place hold that I have step up on the page. How do I alter the class in the Css to prevent this happening

At present

my Css is for the content place holder
#contentholder{
    width: 900px;
    margin-left: auto;
    margin-right: auto;
    background-color: #fff;
    border-top:3px solid #86C67C;
    border-left:3px solid #86C67C;
    border-right:3px solid #86C67C;
    border-bottom:3px solid #86C67C;

}
and my class CSS is the same as the example provide in the book
#newsItem
{
    float:left;
    padding-top: 1.0em;
    border-bottom: 1px solid #488214;
    }
#newsTitle
{

    font-size: 110%;
    /*
    float: left;
    */
}
#newsDate {
    font: normal 0.8em/0.8em 'Lucida Grande', Verdana, Geneva, Lucida, Helvetica, Arial, sans-serif;
    float: right;
    /* clear: right; */
    color: #488214;
}

Can someone tell how I can fix this. Plese