The project file for this tutorial can be downloaded here.
Step 1: In the Workspace Inspector create two or more layers. Select the top layer to inspect it and modify its composition controls.
Tip: To open the composition controls for the layer in its own window click the expand button.
Step 2: Adjust the composition mode and opacity settings to control how the layer is rendered over the layer below it.
Tip: The OpenGL blend modes are faster than CoreImage and Quartz Composer composition modes. Use them when possible.
Step 3: Click on the 'Size & Pos' and 'Rect' tabs, then change the layer dimensions using the width, height, x and y sliders.
Step 4: Click on the 'crop' tab to modify how many pixels are trimmed off the top, bottom, left, and right of the source image using the provided sliders.
Next in this series, check out the tutorials on applying a mask to a layer or perspective correction.
Changing the blend mode of the top layer.
A three layer setup using blend modes, opacity, size, position and crop controls.