Help with PHP coding in Post Content

[joeykissimmee]

Don't really know if this is the right place for this question but here it goes.

What I'm trying to do is insert an HTML code in a post I wrote for my blog. Can't seem to figure it out.

Best way to explain it is the example below:

PHP Code:

#dd_ajax_float{
    background:none repeat scroll 0 0 #FFFFFF;
    border:1px solid #DDDDDD;
    float:left;
    margin-left:-100px;
    margin-right:10px;
    margin-top:10px;
    position:absolute;
    z-index:9999;
} 


When I try to show some coding on the post, the code disappears when I go live.

So basically I want that box to show coding or anything else I want.

My site is http://incomepress.com and I'm using the Generate theme.

Thanks in advance.
Joey