While I agree with all of the above in
theory, if you're an absolute novice who simply wants to get the basic idea of how computer programs work, QBasic is an excellent starting point, IMO. Keep in mind that you'll need to learn another language to write serious programs, but QBasic is an extremely simple and hence useful way to learn the fundamentals of programming.
The compiler, which is a program you'll need to write programs. Click on "compilers" in the menu to the left, and then click on QBasic 7.1.
A great tutorial site.