Renamer runs as an After Effects extension, opened from the Window menu under Extensions. Its operations apply to the items selected in the project panel, and if nothing is selected they apply to all items instead.
Renaming works in two modes you switch between from the Rename menu. Find and Replace searches for a value and swaps it for another, and it is case sensitive. Custom function rename reveals an Edit button that opens a renaming function following the naming convention used at Bending Spoons; the function is editable, and a default example naming convention script is included to build from.
For output, the Render button lets you set a folder for the comps you want to render, then adds them to the Adobe Media Encoder queue using that path. The output path supports a few tokens: [root] is replaced with the path to the current Adobe project and errors if the project is unsaved, [YYMMDD] inserts the current date, and .. moves up one folder in the hierarchy.