Easy!
Thats easy! first u need a camera if u dont know what that is you should learn a bit more.
The camera needs to be adjusted to your first person type veiw -- distance, rotaion so on.
Next u need to have a trigger like so:Camera - Lock camera target for Player 1 (Red) to (Triggering unit), offset by (0.00, 0.00) using Default rotation
Copy that and paste as text. Its on map instalization.
This is how the trigger should look
Events: map instalization
Condition: whatever
Trigger: camera: lock camera to (unit)offset by: whatever, whatever using whatever rotaion.
Next u gotta change his camera:
So u just say apply camera object (name of first person veiw camera)
If u do a cinimatic u have both triggers at the end of them or else it wont lock correctly.
Stopping a palyer from unlocking:
Every 0.01 seconds
Condition: (If u wan cinimatics u should have a condition (bolean) that the cinimatics set to stop this trigger)
Lock camera to (unit) offset by(whatever, whatever)
And thats about all.