Changing CCS from fixed-width to flexible

Hello–

I try to modify a theme from fixed-width to flexible but I got stuck. The theme initially had 3 column: 1) for left sidebar, 2) for content, and 3) for right sidebar. I illiminated the right column. But I do not know how to make the content column float left aside from the left column. Here is the CCS code:

#left {
	float: left;
	margin-left: 10px;
	width: 1100px;
}

#content {
	float: right;
	width: 880px;
}

Thanks!