Any introductory book on a programming language will enable you to read a program written in that language. So go and find the public library or the bookshop and start learning.
It's not really different from learning to read French or Swahili or Spanish or Russian.
Let me give one example of a program. You'll get the idea.
10 PRINT "HELLO WORLD"
This is a full and complete program in a programming language called GWBASIC. All it does (when run) is to put HELLO WORLD on the screen (that's what PRINT does in this language).
The same program in well formed html:
and in not so well formed html (a real life example from http://www.bita.nl, and it's the full contents of their site, to be exact)
Note there are many different programming languages. You don't tell which one you are interested in, and why. If you tell more on what purpose you want to reach, we might be able to give a few more hints.
Hope this helps.
I have a microsoft windws computer, and I am trying to find out how to read source code. I've tried surfing the web, but all the sites I've found assume that anyone who knows what source code is knows how to read it. Could someone please point me in the right direction: where can I fnd out how to read source code?