The Working Life task asks students to select about 6 highlights of a typical working day. Looking at what you actually do on most days will help to provide a basis for future modules, as well as explaining your work role. If you choose to do a 500 word essay, rather than the suggested photo story, then the structure could be a paragraph each for:
An introduction - your job title and context
One paragraph for each of about 6 highlights
A conclusion, revisiting how the six highlights relate to your job title.

If you are drafting a photo story, keep the explanations down to captions, rather than paragraphs.