Rakudo is hosted at github at http://github.com/rakudo/rakudo/tree/master.
The Perl Request Tracker (RT) system is used to track bugs and tasks for Perl 6 and Parrot. You will need a BitCard account to be able to modify tickets through the web interface. You can get a BitCard account if you don't have one already. You can just browse the bugs anonymously, however.
If you want to submit a bug, just send email to rakudobug@perl.org, which will open a ticket. There is no way to open a new ticket through the web interface. When reporting bugs, please try to include (the more of these, the better):
git rev-parse HEAD or by taking the first line from git log)Once you've got your bearings in RT, you may want to have a look at the RT command-line interface.