You will need to present three public seminars to achieve one of the milestones on your PhD. Once you have decided with your supervisor on presenting a PhD seminar with a particular topic and wish to present on date X, then you can follow the process below to make it happen. Go through this link to familiarize yourself with the process. Importantly, note the following two things:
Step 2: Book a room following the process on the CrySPWiki link for it.
Step 3: Email the CS Grad Co-ordinator for PhD programs (look up here), who is currently Loc Thi Do, about your seminar. A pre-designed template for this email is provided on the link above.The co-ordinator will post this seminar on the webnotices.
Step 4: Remind the CACR representative (who is currently Miti), either physically or through an email, to send an email to the CACR mailing list.
The CS Grad Co-ordinator for PhD programs should be able to help you with other inquiries about your PhD seminar.