Synchronizing Text/File I/O

Question

A beginners question and I'm not sure how to phrase it or do a proper search, so I'm hoping someone can point me in the right direction.

I'm writing a program that reads a rather large text file (20,000+ lines) so it takes a few seconds to read the data in.  So I decided to put up a couple messages, like "reading" and the file path.  My problem is, even though I initiate the messages first, before reading the text file, the messages don't show until the file read is complete.

So is threading the area I need to go to?  I vaguely remember using semaphores in C some years ago.