Just click on the node you have in the right window and then click on file out. A screen will pop up, and you can choose the directory you want to put the file in. Just remeber once you name the file have .avi after it and also select it in gobals on the bottom rigfht. Than click on the file out node on the right and select render selected file out nodes, type in the frames and all that.
That should do it.
I am enough of an artist to draw freely upon my imagination, knowledge is limited, imagination encircles the world. (Albert Einstein)
https://www.artstation.com/kurtb