FAQ:How do I log in? What is my username and password? What is the root password?
If you're seeing a login prompt after installation, something went wrong (probably your graphics card wasn't detected correctly).
You should be taken right to a graphical desktop (of course, once in the desktop, you can configure it to act more like a traditional Linux/Unix system and set passwords -- just launch the user manager or, if you like command line tools, open K -> System -> Command Line Interpreter (Super User Mode) and use passwd).
The default username is 'arklinux' and the account is disabled, meaning you can log in only through autologin unless you set a password using the user manager. The root user (superuser) is setup in the same way (password disabled). The arklinux user has special capabilities (provided by the kapabilities tool) that allow it to perform certain (configurable) tasks normally only available to the root user (such as installing packages, stopping/starting network interfaces, running graphical setup tools, or opening a root shell without autolaunching a script -- nothing a malicious script could exploit).
Additionally, the arklinux user has the capability to log in on a local text mode console without a password, allowing you to log in to text mode if something went wrong.
This is not a security problem, assuming your machine is not physically accessible to malicious users -- if it is, we recommend turning the autologin feature off.
