Yes the link given will explain it well, however if u need another detailed explanation then here it is
Firstly to use custom fonts in your app you need to download font files, you can try https://www.1001freefonts.com/ and look for fonts
Few of the most popular font file formats are mainly .otf(Open Type Format) .ttf(True Type Format) .woff(Web Open Font Format)
You can move the downloaded fonts to your app folder under app/assets/fonts/
After downloading the file you need to "declare" the fonts you will be using in your css like this
@font-face { font-family: "Kaushan Script Regular"; src: url(/assets/KaushanScript-Regular.otf) format("truetype"); }
Finally you can use the font-family that you just declared wherever you want like this
#e-registration { font-family: "Kaushan Script Regular"; }
Hope this helps.