Say you have a page called "B"and want to display its content on page A. You type {{:B}}
See the source code for an example. The below text is from another page
Here is how a signature looks: --Norlow 15:59, 23 September 2008 (UTC)
If you look above the editing window (when in editing mode), there is a (user) name and timestamp. If you want to sign whatever, just press the second button from the right --- it says "your signature with timestamp".