RewriteCond %{HTTP_HOST} !^chanpuru\.org$ [NC]
RewriteRule ^/(.*) http://chanpuru.org/$1 [L,R=301]
Put that in a file named ".htaccess" (note the leading dot) in your public_html folder. What it'll do is read the HOST used by the browser to connect to the site, if it's not EXACTLY "chanpuru.org" it'll redirect the request to chanpuru.org, with a status code of 301 (which means "moved permanently.") This is just modifed from some old stuff I had laying around, so it's not tested recently. Try it, let me know if it works or if you have problems.
EDIT: Note that when I say, "exactly" it means
www.chanpuru.org will get redirected as well. That shouldn't be a problem, so long as that's how you want it. If you want softer filtering, remove the caret (^) from in front of chanpuru.org on the first line, as it marks "line starts here." Then it won't alter anything where the host ENDS with "chanpuru.org" If you want the www. prefix to be the default, it might be wise to change the second line to
www.chanpuru.org too. (Me, I hate typing needless w's.)