This is a fairly easy process. But this looks like 3 pictures to me, not 2, so I'm going to explain it as if there were 3.
Step 1: create a new blank PhotoShop document/banner.
Step 2: Open up the "bottom" JPG (in the picture you use as the attachment, it appears to be the keyboard. Select the JPG and copy/paste it to the new blank document.
Step 3: Repeat Step 2 with the second image (the monitor).
Step 4: Open up your "Show Layers" dialogue box. Select the layer you want, and adjust the "Opacity" to something in the 50% range. This will make that second image approx. 50% transparent and therefore partly allow you to view the background image. This is the key step here.
Step 5: Repeat Steps 3 and 4 with the third image (the stuff on the left).
In other words, bring in one image, then bring in a second image and adjust the opacity. You may also wish to play with the "Normal" option to see if the other options in that box help. They can create some pretty cool effects.
Hope this helps.
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