If this is your first time logging into Koha, you should now go to Koha Administration and set up all system preferences, patron categories, item types and libraries. You should also review the other settings found in Administration.
Once you have set up patron categories, you should create a new user in the Patrons module with superlibrarian permissions. Once that user is created, you should log in as that user rather than the root user which is set up as part of installation.
Here are some other places to look for more information about how to proceed:
You can edit the online help through the Koha Staff Client by clicking the "Edit Help" button. This feature has been designed so that library workflow and policies can be documented within Koha.
IMPORTANT: Your online help will be overwritten by the new Help when there is an upgrade. If you want to keep a copy of your online help, you should instruct your System Administrator to upgrade the Online Help directory in the Koha file tree.
The online help directory is:
/intranet-tmpl/prog/en/modules/help
See the full documentation for Koha in the manual (online).