Good news: Lightroom already tags your photos by itself. When you type something like "dog" or "beach" in the search bar at the top, Lightroom finds photos by what is in the picture, so some searches work with no extra work.
To make your own photos easier to find, here is what I do:
Add keywords. Select one photo or many photos at once, open the Info panel, and type keywords in the keyword box, for example: travel, italy, 2024. Good keywords are the easiest way to find groups of photos later.
Use star ratings and flags. Give your best photos stars or mark them as picks. Then you can filter by rating to find them fast.
Add titles and captions. A short title or caption also shows up in searches.
Use albums. Put groups of photos into albums, for example "Family trip 2024". Albums are easy to open and they sync to all your devices.
Use the filters. Next to the search bar there is a filter icon. It lets you narrow results by camera, lens, rating, date, location, and file type.
The search bar checks keywords, titles, captions, file names, and the automatic tags. You can type more than one word, like "italy beach", to narrow the results.