Firstly I import the the beach picture as my background.
I then add the Lion on top of the beach picture.
I then add in the 'sixteen- point garbage matte' on top of the Lion.
I then click on 'effect controls' on the top bar and click on the square by 'sixteen- point garbage matte' then click on the circles to crop the Lion.
Once the picture is cropped as I want I then add on 'ultra key' then go to 'effect controls' and click on the pen by 'key colour' and click that and then click on the green around the Lion.
Once I've clicked on the green around the Lion it gets rid of the green around it.
This is what the end product is, in having a go at a green screen task I now know how to do it and can use it in my own music video if i wanted to.