The app is pretty simple to use thanks to its clean interface but it's not recommended to 'play around' with it if you're not exactly sure what you're doing, since you could seriously harm your device. At any rate, the app tells you this itself the first time you open it.
Official TWRP App makes it significantly easier to install a recovery on your Android. You just have to search for your device on the list, download it, and install it. The whole process takes only a few minutes to complete.