Log in to MailChimp
and after logging in, click on Automations and then Transactional Email
Continue with clicking on ''Launch App''
and then in the dialog, click on Continue to Mandrill.
In the new tab, Mandrill will open
Templates can be graphically shaped with a simple editor in MailChimp as well - instructions
If you would like to prepare templates directly in Mandrill, the procedure is described below:
Go to "Outbound" and after choosing "Templates", click on "Create a Template"
In the ''Name'' field, enter the name of the template (name it meaningfully, since MetaKocka can still see it through integration) 
Fill in the ''Subject'' field as well as the e-mail content.
Click on the ''Publish'' button once the editing/creation is completed.
Below are attached templates "subject" and "vsebine" which you may edit/shape (optional) - you need to be cautious and avoid copying content placeholders that are inside the text and are shown as *|xxxxxx|*.
example: *|customer_name|*
Supported placeholders, which you may insert into the template, are presented in the table at this link.