Here are some useful YouTube videos explaining how Aperture, Shutter Speed, and ISO work on DLSR camera.
1) Aperture Explained: https://www.youtube.com/watch?v=YojL7UQTVhc
2) Shutter Speed Explained: https://www.youtube.com/watch?v=7R9ZTxoTOSk
*A shutter speed tip is to set your shutter speed to double your frame rate. Setting a shutter of 1/60 for a 30fps video will create natural motion blur that will look as realistic on camera as it does to the human eye.
3) ISO Explained: https://www.youtube.com/watch?v=q8cj9Lj9w-g