I sublayout is about Events. If I put it inside a page which contains an Event, it will display informations pertaining to it.
I want to add a Data Template to my Sublayout that will allow editors to specify one particular Event from which to draw these informations.
How do I go about creating a Data Template that allows an editor to choose a specific Event from a list? How do I add this to a given Sublayout?
When building componentized architectures as you are doing, you will want to implement the datasource property for a sublayout to make your sublayout a datasource-driven sublayout.
This article by John West should help on how to set a datasource: http://www.sitecore.net/Learn/Blogs/Technical-Blogs/John-West-Sitecore-Blog/Posts/2010/11/How-to-Apply-Data-Sources-to-Sitecore-ASPNET-Presentation-Components.aspx
The basics are:
The following post by Mark Ursino is helpful in seeing the code side as well: http://firebreaksice.com/using-the-datasource-field-with-sitecore-sublayouts/