The links shown in the first image on the previous page contains the “Find current or past coworkers”. Clicking that link will let you enter your workplace name (Image 8 below).

If, for example, you work for Facebook, start typing Facebook in the Company text box. You will be provided with a list of companies whose names match with the letters you type in, and those which Facebook already knows about. If your company is in that list, great! You may or may not provide a name for the person you are looking for in the Name text box. If you don’t, then all the persons registered from the company you selected will be displayed.