There are many tutorials that teach you to join two images using Adobe Photoshop CS5.1. In this program there are several ways to perform the same action. There are some videos on the internet where you can learn how to join two images to make different operations. The method described in this article is very simple and fast. To follow it, you can quickly adjust two or more images in a single frame and get the result you want.
Steps

Step 1. Open Adobe Photoshop CS5.1 and choose options to open the frame
To do this go to File > New. Enter the exact resolution values you need. In this example, the values chosen were 800x600 for height and width.

Step 2. When the screen is open, click File > Place
A new pop-up window will open and then select the file you want to merge with another one.

Step 3. Now place the file exactly where you want it on the screen
You can reduce the size of the image and adjust it anywhere you want to place it by dragging and dropping it using the mouse cursor. Once you've placed the image exactly where you want it, right-click it and select the Place option. The image will be positioned and the adjustment box will be removed. If you want to remove the image, click Cancel.

Step 4. Now you can add the second image to merge with the first one
Repeat step 2 again to place it and once you have chosen the second image adjust it with the mouse exactly as you did with your first image.

Step 5. After finishing the adjustments, right click on your second image to place it on the main screen
Now both images are on one screen.

Step 6. To save this screen go to File > Save
A new window will open and ask for the format and size you want to save the images for export. You can save it as PSD format if you want to add a little more work to it using Illustrator or any other software. There are many formats available.

Step 7. Once you finish saving the image, it will appear in the desired location
The images are yours now.
Tips
- You must choose the right screen size to place the images if you want a big screen. After choosing it in the first step you cannot change its size.
- Although you exported the image together, you can't change it unless you reopen it in Photoshop. The only thing you can do is save this project in PSD format so that you can later modify it.