The training library holds exercises, sessions and collections from several sources at once. Which source you are looking at is a sub-navigation choice, and searching within it is a separate control.
Where the content comes from
Browse — everything you have access to, in one view.
Your content — what you created yourself.
Team — shared with the group you are in.
Club — shared across the organization.
Curated content — content selected for your organization.
360 Library — ready-made exercises and sessions from 360Player.
Narrow a view down
The search field matches on title and on tag, so searching passing finds both an exercise called "Passing under pressure" and anything tagged passing.
Filters narrow by content type, tag, number of players and more. They apply on top of whichever source you are viewing, not across all of them.
Open an exercise or session to see its full detail, and file it in a collection from there.
Search while building a session
You do not have to leave the session you are editing:
Click Add exercise in the block you want to fill.
Choose Add from library.
Search by title or tag and add what you find straight into the block.