The Community Projection map shows the average of the predictions that U.S. 270 users have posted. It looks like a normal electoral map, except it is not historical, not scientific, and should be regarded as for entertainment purposes only. There’s nothing stopping you or anyone else from making unrealistic or ridiculous predictions. If you wish to add your predictions to the average, you’ll need to be logged in. Your predictions are anonymous, but login is required to prevent people (or Russian bots) from voting more than once. Once you’re logged in, go to Your Prections, look over your predictions, open the menu and then press the green “Post Your Predictions” button.
You can update your vote at any time, but as I said, you still have only one vote. That’s how democracy works. You’ll need to install the app to see the Community Projection. It’s not displayed on this site.