How to change the style of latest posts in HOME page?

How to change the default style of latest posts at home page ?

From this:
http://i1349.photobucket.com/albums/...ps734140f2.jpg

to something like this
http://i1349.photobucket.com/albums/...ps97013a5e.jpg

It's seems to be simple but tricky.
I tried ATO>Style post & Pages> Post Container
and adding this

/*
margin: 10px 10px 10px 0px;
width: 200px;
height: 400px;
position: relative;
overflow: visible;
float: left;
*/

But the result was messy and also affect the contents of the posts. I just want to affect the HOME page.