ATO is shorthand for Atahualpa Theme Options
you need to learn a little about CSS and what each of the options you want to use do. Here is a sample of code you can put in the ATO-> Page/Page Styling -> Post Container to play with:
HTML Code:
border: solid 2px #000000;
padding-top: 0;
padding-bottom: 10px;
padding-left: 10px;
padding-right: 10px;
margin: 0 0 30px 0;
background: #e2e2e2;
-moz-border-radius: 30px;
-khtml-border-radius: 30px;
-webkit-border-radius: 30px;
border-radius: 30px;
If you want to know what each one does, do a google search with the term you want to know about and 'CSS'