how to copy a file within sharepoint using a CRM plugin/workflow(C# server side code).

Hi.

I am creating a CRM plugin(will later convert into a workflow, basically a C# server side code), that is supposed to copy an entity record changing a few fields along the way. now one of the fields i need to change is the sharepoint URL of a document. i know that simply changing the URL will lead to a file that does not exist. so i want my plugin to connect to sharepoint, "copy" a file located somewhere in sharepoint(known URL), and "patse" it to a new URL that is also known/i'll write it as needed. and only once that is done, change the "sharepoint URL" field of the record to the new URL(i know how to change entity record fields)

anyone has an idea on how to do this copy/patse operation? i tried to find an answer all over the internet and i saw some CRM/sharepoint connection things but none of them is what that i want to do