Click in the track mixer (Window - Open Track Mixer or CTRL-M) and check for the Master track (this one is the only one which will have a BNCE button instead of REC. It typically is just before your midi mixer.

Make sure you are able to see the whole track mixer by maximizing your Logic window and stretch, if needed, your track mixer.

If you do not see it, go to Tracks menu and make sure Add Master(s) is check marked. If not, check mark it and look again.

If you still do not see it, there is a way around it:

1. Go to Windows - Open Environment.

2. Select AUDIO where Click & Ports is or Midi Inst. is. This will bring up your environment's track mixer.

3. Scroll all the way to the right. There should be several Master mixers, each with a BNCE button. You can bounce from here.