Two handed rods are used mostly to swing flies down and across the stream but some use them as effective nymphing rigs also. The extra length of the rod helping in that cause. I prefer swinging with the long rod myself. Cast across slightly less than 90 degrees and throw an upstream mend into the line to help your fly sink. Let the fly swing across the current following it with the tip of the rod. The idea is to "swim" the fly just above the bottom. Skating flies with a floating line is also a great way to fish with a two hander. You will know when a fish hits.
Casting is the key and the hardest thing for people to learn. Learning to cast a two handed rod from videos is possible but is going to take some considerable time and likely quite a bit of frustration. Hopefully you won't get discouraged. If it is possible find someone that has some experience casting a two hander to help you. It is not as easy as it looks.
"The reason you have a good vision is you're standing on the shoulders of giants." ~ Andy Batcho