There are some trauma handbooks out there but the best ones I've seen are "in house manuals" - ie, produced by the hospital themselves. They give local policies (ie, who gets transferred to Ortho or do they stay on Trauma service).
Otherwise, you'll have passed ATLS and know your primary and secondary surveys. Review the trauma section in your general surgery book and when you are in the CT scanner make sure you look at the images with the radiologist to become more comfortable reading them (a necessary skill as a senior resident).
As noted above, you won't be in there alone - look to the Chief for direction before drawing labs, putting in Foleys, etc. But be prepared to step up and do the primary survey, help move the patient over, get them undressed, etc.
My major pet peeve was ignoring the "minute of silence". When EMS brings a patient in, I (as the Chief or attending) need a minute of silence to hear the report from the transport unit; if you jump on the patient and start yelling out, "airway clear", "breath sounds bilaterally", I can't hear a darn thing the guys are telling me about what happened, when, and how. Unless I tell you to get started, the patient is not going to (in most cases) die in that minute. Even if he was, it wouldn't change the natural history.