This is a rather simple operation. All you need to do is unbend three plastic locks on the right side of the front panel. Then take the front panel off carefully – the locks on the left side may be damaged by a hasty movement. Next, take the drive and attach the rails to it:
And then insert it into the bay until it snaps in place:
The 3.5” bays are covered with special brackets which must be removed before installing a device:
The procedure is the same as with optical drives – attach the rails and insert the drive into the bay.
The installed drive doesn’t stick out much from the front panel: