Here is an easy beginner's composite project I worked on this weekend that I want to share with those who may be wanting to learn how to composite in Photoshop, but just don't know where to begin. This is performed using Photoshop CC (I used LR 5 for basic edits).
Here are the two images I used to composite the final product:
STEP 1: COPY & PASTE
Use the Rectangle tool to draw a square around either of the images. Press CTRL + C to copy the image. I usually do this a few times just to be sure I have it copied. Click on the second image and press CTRL + V to paste it on top of the image. You will see two layers in your layer window after pasting. At this point, I make the opacity of the pasted image 50% and also use the SELECT tool to move and transform the top image so that the stars arms all match up. After they are as close as possible, I move the opacity back up to 100% and move to STEP 2.
STEP 2: MASK IT OFF
click on the LAYER MASK button at the bottom of the layers window to add a mask to the pasted image. Use your BRUSH tool with the color set to black (black reveals, white conceals) to brush off the part of the image you want to reveal what's underneath. For example, I wanted the ring on the bottom image to show through so I brushed off the top and right side of the image with the hand on it to show through the bottom image. This reveals the part of the first image that had no hand on the star. Now I have no hands holding the star. Remember to zoom in using the MAGNIFY tool to pay attention to the detail around where you mask to be sure everything matches up. For the purpose of this photo (to sell the ring) I sharpened the ring a bit before flattening the image for our next step.
STEP 3: FLATTEN & SHARPEN
After flattening from the prior step, press CTRL + J to duplicate the background layer. In this step we are going to sharpen the whole image by adding a HIGH PASS filter. To do this click on FILTER, OTHER and HIGH PASS. Set it to 3.5 and click ok. The layer will turn gray but don't worry! Click on the BLEND MODE above the layers in the layer panel by clicking on the drop down arrow by the word 'Normal' and change it to OVERLAY. Flatten again and we are on to the final step!
STEP 4: CROP & CLEAN
You won't always crop an image (I almost never crop) but in this image, I am cropping for composition. First I am going to clean up the pesky little white dots at the bottom from the starfish using the CLONE STAMP tool. I'm going to flatten again from the high pass filter layers, then duplicate the background layer again using CTRL + J. Select the clone stamp tool on the left toolbar (looks like a stamp). Then, with the background layer selected, choose an area of the background you want to use to cover the spots. Choose this area by clicking on the area with your mouse while simultaneously pressing the ALT key. Next, select the top layer and brush over the spot to cover it up. You may have to keep moving the clone selection if you come close to an area that doesn't match the area you are trying to cover, just make sure to click on the background layer to reselect your cloning area. Once everything looks clean, flatten and voila! You are done :)
This concept is basic for compositing. Use masking to add animals, skies and much more to your images! There are many ways to do this but this is how I like to composite images with simple backgrounds. For much more complex composites I will use the lasso tool to draw around a piece of another image to add to my main image as well. Play around with this concept and have fun with it!