LOL I didn’t either when I got started. Basically Medium has a panel of 25 people that comb through submissions daily and make their selections for the “best” ones and choose them for curation under a “tag”. For example, my first article chosen for curation was this one: https://medium.com/invisible-illness/can-a-bullet-journal-help-your-ocd-7617d8864c1
It was chosen to be curated under “mental health” and under “productivity” tags — meaning this article will now be more visible on the site and more people will see it, not just your followers or people who happen to run into you somewhere and go looking for your articles.
Under the Medium help tab, you can search for curation requirements — they look for a very specific style of article.
Also, separate from curation, you can be awarded a Top Writer status in a tag you post in and do well, frequently. Limited spots are available for these positions. The day AFTER I posted this article I was awarded Tope Writer status for Poetry, a very competitive tag.
Hang in there…just keep learning!