float content differently on different pages

Newbie alert. I am using customizr child theme. My website is http://sproutedjourney.com. I would like to know how to float the main content on my page differently for different pages. Right now I would like the home page, which is a static about page, to float left and I want most other pages to float right. I would also like to figure out how to change the width of the text inside the border radius if possible, right now the text is too close to the edges.
For the floating issue I am using this code (which only works for ALL pages to look the same):

.span9 {
width: 868px;
float: right;
}

and

For the border-radius I am using this code:

.span9.article-container {
border-radius: 10px;
background: #FAFAFA;
}

Thank you!!!