Use the Really Simple SSL plugin to move your wordpress site over to SSL.
This is the code that is added to your htaccess file to force the 301 redirects.
# BEGIN rlrssslReallySimpleSSL rsssl_version[2.5.20]
<IfModule mod_rewrite.c>
RewriteEngine on
RewriteCond %{HTTPS} !=on [NC]
RewriteRule ^(.*)$ https:// %{HTTP_HOST}%{REQUEST_URI} [R=301,L]
</IfModule># END rlrssslReallySimpleSSL