If you are a new student, you will be allocated to a student group during induction week. That is one of the reasons why it is crucial for you to attend your academic induction sessions!
If you are a returning student, your student group is likely to be determined by your module choices.
If you want to talk to someone about student groups, you can contact your Course Leader. His / her details will be in the Course Handbook on UniLearn (Blackboard).
However, even without knowing the exact group, you can still learn some things about your timetable online: