As explained in About searching this site you cannot do a single search covering all the items in this site. You need to search each of the sections within the site. This page covers media, notes and sources.
The basic procedure in searching pages like media, notes and sources is the use of this dialogue box:
If you leave the search box empty it will list all items. Otherwise type in what you are looking for. TNG will search all the fields. For example, if you type "ancestry.com" in the Sources search box, it will search the title, author, publisher, etc.
Media covers all the items covered in the Media drop-down menu:
You can search a particular media category or "All media". (Recordings and Videos are so far empty but I have left them in the menu to encourage you to send some in!)
You will notices that the search result for Media items contains a link or links to people who are connected with the items you have found.
Notes appear under the Info drop-down menu. They appear in all sorts of places in the family tree data. Of particular significance is the fact that information about a person beyond the statistics (birth, marriage, death, children, etc.) is in their Notes. But they appear in other places and are well worth a search. For example, want to find who served in World War II? Search for "WW2" - I know, you need to know that this is the term used but you will have found that after a few tries!
Sources are where the information comes from. The link can be found under the Info drop-down menu. Sources can be certificates, wills, email correspondence, web sites (there will be a link to the web site if it is still current), books, newspapers and periodicals, etc.