You must choose a host name that you would like to secure e.g. www.names.co.uk or admin.names.co.uk. Notice that the sub domain (in bold) for each of these examples is different.
An SSL certificate will only secure one host name. For example, to secure both previous examples, you would need two certificates, one for the www.names.co.uk host name, and one for the admin.names.co.uk host name.