Groups in OpenHab2 - Beginners question

As a beginner (ive been using openhab2 for about a week), I am trying to find if thee are any tutorials regarding “Groups” in Openhab2.

i think I have read all the available documentation and it still baffles me. One of the main questions is, where do you define the group is it in the sitemap or the items file.

I am trying to do something like this

House (Sitemap)
Ground Level
Living Room
Another TV
More Lights
Touch Light Switch
First Floor
Bedroom 1
etc etc etc
Living Room
etc etc etc

Groups are defined in the .items files, but they can be used in .rules files and .sitemap-files.

Have you had a look at his page?

Thanks for the reply. Yes I looked at that but it didnt make much sense. I was presuming it should be in the site map file as that looks like the file which makes the GUI front end. Im having problems visualizing how i set up a nice front end with the items categorized in groups

Its in the Item file then you expose the group item in the sitemap

its all here with examples:

Thanks guys, ill take a look at those links. I just noticed that my original post had the groups “UN-indented” so probably made no sense at all.