The easiest way to incorporate social sharing into your NUsites site is to use the AddThis plugin.
On the configuration page, you can adjust which types of sharing buttons appear on your site, and where they appear in relation to your content.
In the Basic tab, you can choose to display sharing buttons above your posts, and display sharing buttons below your post content.
In the Advanced tab, you can make adjustments to which types of pages display these social sharing buttons.