You shouldn't do anything until you've had the lecture for that subject. There are many reasons why the units aren't up yet:
1. That unit may not use blackboard at all.
2. The unit of study coordinator has not yet set up blackboard for that unit.
3. It's not showing for your particular account for some reason (unlikely).
Just be patient - you'll find out during your first lectures whether blackboard will be used, and if it will, when it will be up. If you do find out that everyone else has access to that unit on blackboard then you can email the unit of study coordinator and/or the IT office to fix that up. In the meantime, there should be nothing to fret over.