After Effects - green screen (keylight)

So we began by learning how green screen could be used to manipulate images and video making them into something quite abstract. Here is the process and how I did it:

1) I began by importing the green screen videos given to us into After Effects. I then put them into a new composition like so-

2) I then went into the effects and presets menu on the right hand side and search for an effect called Key light (1.2) and applied this to the green screen layer. I then went into the key light menu which was now in the effects control panel on the left hand side. I clicked on the screen color option and used the pipette tool to choose the colour of the green screen. Once I had applied this it cleared the green screen out and let my background colour show through instead. (As you can see I chose a nice teal colour for my background colour when I was creating my new composition)-

3) Then I clicked on the green screen layer in the bottom left hand corner and in the drop down menu next to it put it from final result to Screen Matte. This let me see the result in black and white. I used this view to go into the effects control menu and open up the screen matte menu to allow me to change the black and white values so that instead of having grey detailing it was all simply just black and white like so-

(once you've finished doing this you need to click back to final result instead of screen matte)

4) Next I used an image of my choice and inserted it in to this composition/timeline making sure it was underneath the green screen layer. Then I needed to click on this image layer in the bottom left and select the drop down menu which currently said none and click on the setting in this menu that says Alpha Matte. This then makes that image appear within the subjects rather than the background-

5) To extend this piece further I then duplicated the green screen layer on my timeline/composition. I then dragged this duplicated layer to the bottom so that it was underneath the other previous layers. I then chose another image that I wanted to combine with this and imported that into my timeline/composition again underneath all the previous layers. And then I changed the setting of this new picture layer to Alpha Matte the same as I did the first time. You can currently not see the image you just imported as it is now hidden underneath the first image layer. To make it layered up you can either go onto the top picture layer and change the opacity or what I did was go onto the menu which has all the blend options and I used a layering style called Screen. Here are the results-

6)To add more interest to the piece I wanted to layer an image with my background too so I chose another image and imported it in to the timeline/composition. I made sure it was underneath the previous layers and it automatically set itself as the background. I then changed the opacity of this background picture so that it was combined with the blue background colour creating more of abstract piece.-

7) To finish it off I then played around with animating the picture layers through skills I had learnt before. For example I change the scale of of one of the images and keyed it so it slowly increased during the piece. I added some position animation to the background layer as well. Here is the finished piece: