Download .ts file and copy into your project then use below div tag in your Html.
<div appParallax imgSrc="path-to-your-image" imgHeight="70vh" bgSize="cover"></div>
Use below options in your html tag
imgSrc // path to your image
imgHeight // backgound height. default is 70vh
bgPosition // background position. default is 50% 0
bgSize // backgound size. default is cover