There are several resources around the net that show how to do this. Here's a code snippet provided by http://www.inmotionhosting.com/support/website/redirects/setting-up-a-301-permanent-redirect-via-htaccess
RewriteEngine on
RewriteCond %{HTTP_HOST} ^example.com [NC,OR]
RewriteCond %{HTTP_HOST} ^www.example.com [NC]
RewriteRule ^(.*)$ http://example.net/$1 [L,R=301,NC]
If this doesn't work for you, here are some other resources:
https://www.internetmarketingninjas.com/blog/search-engine-optimization/301-redirects/
https://css-tricks.com/snippets/htaccess/301-redirects/
http://www.bruceclay.com/blog/how-to-properly-implement-a-301-redirect/
The first code example is more canonical friendly. The simple version I see used a lot and recommended in the other resources I've provided looks like this:
RedirectMatch 301 ^(.*)$ http://www.xyz.com