Per their API:
Markup:
<div id="aceEditor" style="height: 500px; width: 500px">some text</div>
Finding an instance:
var editor = ace.edit("aceEditor");
Getting/Setting Values:
var code = editor.getValue();
editor.setValue("new code here");
Based on my experience, Ace is the best code editor I've seen. There are few others such as CodeMirror etc. but I found them to be less useful or difficult to integrate than Ace.
Here's a Wiki page for comparision of such editors.
There is a paid one also which I haven't tried (and I can't remember for now). Will updated later if I can find it.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…