Giving some guidelines isn't too much to ask imo
You'd need to do the following steps (might miss one or two, it's early for me
)
1) Make connection with fileserver where update file is located ( /help /sockopen )
2) On connection, send the file request (HTTP request i assume, so you need to study the HTTP protocol to find out how the request looks like) ( /help /sockwrite )
3) Server will be sending the file-data, store this info in a new file ( /help /sockread /help /write )
4) When filetransfer is completed, close connection ( /help /sockclose )
The idea is pretty obvious but the /help <command> should point you to your way.
