Multiple image - using layers in Photoshop

To create a multiple image in Photoshop I have used two photographs of the same cat. I have first opened one of the pictures and used it as a background. Then I have pasted the second picture as a new layer and changed its size and position so that the cat from the second photo was behind the one in the background. I have also added a layer mask to the second layer by clicking 'Add layer mask" button in the Layers window. I have then changed color of the mask to black by clicking 'Image --> Adjustments --> Invert' to temporarily hide the new layer. In order to reveal the cat from the second layer I have used a soft, white brush and painted on the mask precisely the area I wanted to be visible. At the end I have used the 'Brightness and contrast' adjustment layer to darken the top layer down so its brightness was matching that of the background. In order to be able to save the file as a JPG image I have also merged the layers by clicking 'Layer --> Flatten Image'.