To log into the admin panel you direct your web browser to:
YOURWEBSITE/osticketDir/scp
change YOURWEBSITE to your domain name.
change osticketDir to the directory that you put OST in.
It will prompt you to log in, use the username and password you setup during installation.
Once you have logged in, in the upper right hand corner click on "Admin Panel".
Click on the "Settings" tab.
Scroll down to "Alerts and Notices"
make sure that "New Ticket Alert:" is enabled.