You need to make sure tht the user your logged in with has permission to view statistics.
Admin panel -> Staff -> Groups -> Your group.
Can View Staff Stats should be yes.
Once that's done then you can view statistics Staff panel => Dashboard.
There is also the very nice reporting mod that scottro authored available at:
http://www.osticket.com/forums/showthread.php?t=14825(http://www.osticket.com/forums/showthread.php?t=14825)