To place the blade in the saw (step one), you will have the blade at 90 degrees compared to the saw teeth facing inboard.
Then you will place the arbor of the blade inside arbor of the saw (step two), you will be able to see through the slot when the arbors meet and sits down.
Then you will (step three) raise the blade up all the way to sit parallel with the saw and should hear a click sound.
The release button on the saw does not need to be pressed or depressed for loading a blade. Only for removing the blade, the blade release button is pushed in to bring it down to 90 degrees and removal.
Images attached in case by step.