At the top left of your screen, there are several buttons. You have to click on Render, then Render animation. So you will have settings that you can tweak, and then, when you click on render, it will open the file explorer. Select where you want to download the video. Then click done. It will start calculating the video and will tell you how much time there is left. When it's done, you can go to the directory you selected. Your video will be there.