I created a Wikipedia account when I was 19. I was undoubtedly using it before then, but in 2005, that’s when I first felt compelled to edit it.
Before this, my high school teachers were worried about students relying on it as a primary source (because it isn’t). Instead of teaching students how to follow the information to its source and use it properly, they discouraged its use altogether, because “anyone can edit it.”
That phrase never scared me. Instead, it excited me. Anyone being able to edit it makes it the compendium of human knowledge. Wikipedia is like the world’s brain. You receive new information, edit, fix things, and maybe toss out old stuff you know isn’t true.
Over the years, I have made lots of small edits, but I’ve also written entire pages. I’ve made and released images into the public domain for pages to use. When I tell people about this, they’re surprised because they’ve never edited Wikipedia themselves and don’t know anyone who does.
If you’re on a Wikipedia page and see a typo, just fix it. If something’s missing, and know where you can verify that information, add it. You should start editing Wikipedia, too.
Yesterday, one of my favorite Internet People™ made a brisk 30 minute video about how to start editing Wikipedia. Molly White is a much more experienced Wikipedian than I am, so I recommend watching it (and reading her accompanying blog post) if you want to get started.