Booleon equations

I am working on a house and I need to put windows in but I dont know how to use booleon equations. Can someone give me a tutorial I can work off of or show how to use the equations? And what is a C key that I have heard about when it come to booleon equations, do you really have to buy it or is it a hoax?

To use booleens you need to select 2 objects then press the “w” key to bring up what operation you want to use. And about the C-key, before Blender became free you needed one to unlock all the features, it’s no longer needed now unless you DL an early version from the old version page where it can now be DL’ed for free like the program.

ok thanks