SSL Certificate 2048 bit generation with OpenSSL

openssl req -nodes -newkey rsa:2048 -keyout www.examplewebsite.com.key -out www.examplewebsite.com.csr

You'll be prompted for a series of questions:
Country Name (2 letter code) [GB]:AU
State or Province Name (full name) [Berkshire]:New South Wales
Locality Name (eg, city) [Newbury]:Sydney
Organization Name (eg, company) [My Company Ltd]:Example Company
Organizational Unit Name (eg, section) []:
Common Name (eg, your name or your server's hostname) []:www.examplewebsite.com
Email Address []:

Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:

You then upload the contents of the www.examplewebsite.com.csr file to your SSL certificate registrar and they'll send you back your certificate file.  You can then plug these into your favorite webserver/application server.