Most talks, and various other things like jobs are announced in the department's weekly newsletter, the Sesquipedalian, which is distributed by email.
Nearly every Friday at 3:30 during term, the department has a colloquium (``talk'') in Room 146 (the seminar room) of MJH (Margaret Jacks Hall, your home), which is followed by a reception (``food''). As a first year, you get roped into setting up the reception, and so you're pretty much obliged to go occasionally. But really it is a good idea to go every week. You get to learn what fellow students and visitors are working on, and the reception afterwards is probably the best chance you get to talk to other linguistics students.
Roughly fortnightly, there is syntax workshop and phonology workshop, the former always at Stanford, the latter alternating between here and Berkeley. They're another place where you get to hear about the work that your fellow students, faculty members and various visitors have been doing. You can get yourself put on the (electronic) mailing lists for these workshops by contacting sinterest-request@csli (syntax) and pinterest-request@csli (phonology). There are also occasional talks in sociolinguistics (the Sociolinguistics Rap Session; contact basa-request@csli) and semantics (ask yookyung@csli). You're really encouraged to present some of your own work at these workshops. It is excellent preparation for the activity that professional linguists spend much of their time doing, and you can put it on your CV. If you find you have a topic that doesn't fit within one of these neat categories, the organizer of one of them (or your Grad Reps) will be happy to set up a workshop for you.
CSLI sponsors various talks on philosophy, language and computation. There is TINLunch, held on Thursday lunchtimes, and then usually one or two other talks on Thursday afternoons, and sometimes other irregularly scheduled talks. You can read the CSLI calendar on paper by picking up a copy at CSLI, or electronically on the csli.bboard bulletin board. You can also be put on a mailing list to receive it.
Each year, the Child Language Research Forum (CLRF) is held at Stanford, and interested students are encouraged to help run it (and the remainder are cajoled). You'll have a chance to sign up for this and other committees at the beginning of the Fall Quarter. In addition, there are various other occasional workshops and conferences; you'll hear if anything is going on.