If you have any additional questions, don't hesitate to contact me on my stream or via this forum, I'm always glad to help. There are a ton of tutorials on youtube on how to use it. If you wish to show only one of the two images, what you would want to do is run two separate instances of OBS and run one of them in full screen preview mode and use the other to capture half of the preview footage (make sure you set it to 1080p so you don't lose quality). Much like shadowplay it can record and directly stream your game and has a lot of functionality to make things look great. You don't have to rotate anything as it mirrors game footage directly without the need for screen capture which is coincidentally easier on your resources and keeps full source resolution. Both are free to use and have powerful features to back their positions. They are long time competitors that compete for the same audience. OBS Studio and ShadowPlay are two leading live streaming and game recording programs on the internet. I would first of advise against using shadowplay and instead simply use a free open source program called OBS. Finding the right software is a challenging task.

Look at my past footage (please follow) of my twitch stream for examples:

I think I can help you out a little here.

Obs or nvidia shadowplay