how to render video

You need to change the output settings from an image to a video format, then specify the container and codec, click on the 3 dots and dashes for presets.
Those shown below are a standard mp4, then you will need to render animation (CTRL+F12)

And don't forget to set an output file location and if needed change the Frame Range:

(When you get to more complex videos, it is common to Render as Image Sequence and then use the Video Sequencer to turn that into a video, but for now, directly Rendering as Video is the easiest.)