Anybody can contribute, just go read their site which explains what you're agreeing to, sign up and start contributing. If you want to actually create a whole walking trail through a state park that might need tools (on which OSM's site can advise good choices for your platform) but where people's only problem is "The name of my street was spelled wrong" you can fix that from the web.
tialaramex|4 years ago
matkoniecz|4 years ago
Have you tried Osmand/mapy.cz?