Sky replacement used to be something that was quite tedious and took a fair amount of effort and technique to accomplish convincingly, but in the last few years, we have seen a lot of advancement in automated sky replacement features in various applications. If you are new to using them, check out this fantastic video tutorial that will show you the ins and outs of using Photoshop's sky replacement features and how to use your own skies for the task.
Coming to you from Aaron Nace with Phlearn, this awesome video tutorial will show you how to use Photoshop's sky replacement feature, including using your own sky shots. While you can certainly buy your own skies, it is very easy to build your own library; literally all you have to do is point your camera at the sky! You do not have to worry about post-processing them as you take them either; rather, the goal is to simply build up a collection that features a wide variety of lighting situations and cloud compositions. You can always adjust them as needed when you decide to drop one into another photo. Check out the video above for the full rundown from Nace.