Once you order the SSL certificate and paid for it, you will receive an email from support@freessl.com with a subject of 'Please complete your Namecheap StarterSSL order'.
The email will be sent to the email address on your main profile. The email will have link that will take you to a page where you can generate your certificate. The url will be in the format of: https://products.geotrust.com/ssl/partner.do?pin=123
Note: The email will be sent immediately in 99% of the cases. But, it may rarely take up to 24 hours till you receive the email.