Adobe Photoshop CS6 Learn by Video: 5.4:
• Merge two images for one Perfect Shot

Adobe Photoshop CS6 Learn by Video: 5.5:
• Layer Mask, the Key to Flawless Retouching

Adobe Photoshop CS6 Learn by Video: 5.6:
• Creating Special Effects with Layer Mask

Adobe Photoshop CS6 Learn by Video: 5.7:
• Correcting Color & Contrast Using a Layer Mask

• Correcting Color & Contrast with a Layer Mask
• Blend two Images with Layer Mask
• Understanding Layer Mask
• Understanding Blending Mode

Adobe Photoshop CS6 Learn by Video: 10.14:
• Using Blending Modes and Adding Mask

• Using Quick Mask Mode: http://www.youtube.com/watch?v=tQrXYL0LQc0
• Making Selections using Brush Tool & Quick Mask:
http://www.youtube.com/watch?v=KOeOzda1S_c