Focus on the genre of a magazine article - a relevant title aimed at whichever age group you choose to focus on (can be humourous or informative) as well as the page layout expected with an author's name. Language should be context appropriate, not as formal as a newspaper article, but not as colloquial as a blog. Also focus on the key word 'explaining' - most of the content should be highlighting emotions and reactions you had, rather than being overly descriptive of the events.
The description of the discovery should be based on reality (it's not a fictional story!) and again, context dependent. If the discovery is something humourous or less serious, the language used should reflect that, while if it's dramatic more colloquial language will be inappropriate.