A span is an "inline" element, meaning that it's designed to sit within a line of text etc. So things like padding don't work quite the same. One way to deal with this is to give the span display: block; which will make it behave like a block level element. Another option is to use a <p> instead and give it a special class.
Feel free to post your code and some indication of how you want it to appear, and we can help further.