Adding custom fields to sales cycle

I have added custom fields to Sales Order, How these can be shown in Sales Invoice, Delivery Note etc.Where to modify the code.
Thanks in advance.

Are you trying to achieve this? Not Found

You have to add the custom field for every doctype seperately.
If you want to map the custom field of different doctype then you have to keep the docfield name same as mentioned in the link provided by @strixaluco

Thank you both of you @ManasSolanki @strixaluco
Now I have basic knowledge on frappe,How can I master it. Is there any resources