Once you have setup your green screen there are a few things you need to know to produce decent green screen videos where you will be able to easily “key out” the green screen and achieve a professional looking result.
Maybe you thought that you could just build your green screen, install your phone and camera instead of it and start making wonderful green screen videos, but this may prove to not work so well, for the result to be a lot better you will need to place some lights, the lights that you use in your house are not strong enough, I personally recommend getting some work lights. Because they are strong and cheap.
You need to place the lights in a way were your subject will be correctly lit and at the same time, not cast a shadow on the green screen. To do this properly you need at least 3 lights, but most recommend 4. Below are some diagrams that show you how to place them.
As you can see you want at least 2 lights to light your screen behind the subject, so your screen will be bright and easy to “key out” but you also want at least 1 other light on your subject, otherwise your subject will appear very dark.
Finally all you need is something to hold your camera in front of all this. If you have a good camera with a good stand then it’s great. However if you’re like me, on a very tight budget, you can use anything and strap your phone to it. I personally filmed with my phone and strapped it with some elastics to an old broken microphone pole that I had laying around. Of course the better the camera the easier it will be to key out the green screen. For example my phone is an old Samsung Galaxy s2 and its pretty hard to nicely remove the background from the videos filmed with it but when I use my girlfriend’s more recent Nexus 5 phone to film it suddenly becomes a lot easier to key out the green screen and achieve a more professional result.
At this point you should have all the necessary information to setup your own green screen and start filming.
Maybe a few more advice I could offer. If you are filming alone and are using your phone, using your back camera will allow you to see yourself in the camera at the same time as you film, this way you can make sure that you are properly in the shot. But I am sure that you will develop your own technique as you try it.