As of JEvents 2.0+ you should take a look at the JEvents Custom layouts editing tool first - this allows you to customise your event detail and list pages without needing to do any PHP coding.
Click here for more information
So you want to customise one of the layouts provided by JEvents but you don't want these changes to be lost when you upgrade. This is a very brief guide - if you want more general information about template overrides then I'd recommend you search for Joomla! template overrides in a search engine.
Lets assume you want to customise the year list view of the Geraint layout.
Joomla should use this copy in preference to the core JEvents component file from now on and you won't loose these changes if you upgrade JEvents
If you want to customise the latest events module: e.g. Create an override for a latest events module.
You must create the override file from:
Then you need to set it as an Override, so if you were using the Geraint theme it would go from:
class GeraintModLatestView extends GeraintModLatestView
class OverrrideGeraintModLatestView extends GeraintModLatestView
Then customise the layout as you want.
Notice the Override before GeraintModLatestView. If you do not include this then the override will be ignored.
You want to customise the stylesheets or images.
Follow setps 1-3 above and then
You realise you need to change or add a helper function (e.g. the iconic navigation bar)
Follow steps 1-2 from "basic changes"then