Use layer masks to create a compelling photo blend
Identify which layer you want to apply a layer mask to, then go to Layer>Layer Mask>Reveal All. Alternatively, you can click the Add layer mask icon in the Layers palette instead.
Set your foreground colour to black and grab the Brush tool. Give it a high Opacity and 0% Hardness. Paint areas you want to hide, using the left and right square brakets to resize.
You will more than likely paint away some areas you didn’t intend to hide. Switch your foreground oclour to white paint back over those areas. Like magic, they will reappear!
It usually takes some jockeying back and forth between black and white strokes to get a mask just right. Don’t be afraid to zoom in to get a good look. You can lower the Opacity for softer blending.