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.

I didn't test but how about the following in CSS Inserts?

body.home .post {
margin: 10px;
width: 30%;
float: left;
}

I would avoid the height as you would have to add overflow:scroll which I think looks bad.
The above is an example and may need to be tweaked.

Oh man!
Really?
You're a big help!

This was the result my friend:


http://i1349.photobucket.com/albums/p759/bandwidth1/cooltable_zpsd501ee6e.jpg

I need now to put a reasonable height for all the article containers and also that the main picture of every article is centered and without text at the side. Can you give me a hand with that please?

You can use excerpts of a certain length to get the heights close.