Since you're just joining the raid team, /join vindication so members of the guild can easily chat with you. You may also want to talk with Shaala when you see him on, since he's been running most of the raids lately.
Your gear is (understandably, since your lock is a fairly fresh 80) a bit mediocre for current content raids, but if you're a good warlock, you should still be able to be a decent contributing DPSer.