Great work! The website has a great feel to it and it seems like a good first project to get out in the open. Definitely looks/works a gazillion times better than my first website!
There's an issue I'd like to point out that I've seen come up over and over again with people like yourself who've taught themselves to code via treehouse, codecademy or some of the other webdev-education based startups. I've met developers with 10+ years of experience who make the same error though, so I wouldn't beat yourself up too much about it.
This may have been deliberate, but it appears as though you can view all the rewards on the site (including other users) simply by modifying the URL. It also seems like you can modify or delete any of the rewards on the site too (try changing the form action/fields using chrome web inspector and submit the form). Since this is your first rails app and I'm assuming you're not hoping it's going to hold any sensitive data, this isn't that big a deal.
Do keep in mind though that in its current state, it's trivial to create a script that deletes all the rewards on the website or worse, fills all the reward info with spam data.
For the last person I pointed this out to, I put together a gist of what the before => after of the code should look like for fixing this https://gist.github.com/Najaf/5431024 (tl&dr, you need to whitelist those params and implement authorization).
If you'd like any further help with this, feel free to ping me via email.
Best of luck!