Footer below expanded content

Ive been trying to get my footer to stay below the blog content and can get it to sit fine once the content div’s are set to a height pixel dimension but then they will not expand to fit the changing size of the blog posts. I have tried setting the content div to auto/% which makes it expand to the size of the blog but the footer then sits in the middle of the content and not the bottom of the page. I thought I could do this with CSS but so far no such luck. How does this feature work on the default wordpress template? E.G a footer that sticks to the bottom and content that expands and shrinks to fit the blog? Any suggestions of directions to tutorials would be much appreciated