The below video shows the final outcome of the green screen tutorial that I completed. This was my first time working with green screen footage but it wasn't as bad as I thought it would be. Once you understand the process it's quite simple. With the green screen footage selected, I used KeyLight within After Effects to key it out. By selecting the colour of the green screen and adjusting the black and white values, along with masking out the rest of the footage (creating a garbage matte) you isolate the main footage and are able to drop a background image behind it.
For my first attempt I think it's turned out okay, but I know when it comes to keying out my own footage there will be adjustments I need to make and might have to create other masks. I also had to animate the mask path on this footage as he was moving about and his arms would have been cut off if I kept the original mask I created.