In my account you are able to manage your account.
If you want to enable the client certificate login you need to go to My account. In the top menu you find the entry "Add Clientcert with Browser" to add your public key of your CAcert certificate to the application. Only valid CAcert certificates are accepted.
My clientcert items show the stored client certificates.
To ask for an Assurer check your certificate must contain your name as given in your CAcert account otherwise the Assurer check will return "No Assurer". You can ask yor the assurer check at the end of the My account - Edit page. Once you ask for the Assurer check support will try to do the check within the next 2 weeks.
If the entry is not visible you have already the "Assurer" status.
The Assurer status is needed to add an "Offer assurance" entry.