In order to get into the management area of your domain log in to the customer center and select the respective contract.

Under the displayed features in the menu entry "Domain" you are now able to configure the following features:

• Redirect
• DNS Management

Under "Redirect" you can set up  your redirection or forwarding of the domains as well as setting up, changing and deleting subdomains. 

Under "DNS Management" you can (depending on your tariff) look up, create, edit and delete your DNS entries (records).

An overview of available DNS records (depending on your tariff) und information regarding this subject can be found under:
Which types of DNS records are there and what do I have to consider?