How to create a bitcoin price widget is Chapter 7 of my book (a portion of chapter 7 is available in the "look inside" preview).  https://www.amazon.com/Building-Bitcoin-Websites-Beginners-Development/dp/153494544X

Or you can watch my youtube tutorial video on how to create one for free: https://www.youtube.com/watch?v=uVlMueUBGOo

Have fun, and good luck!