If you are a novice with computers and the Internet, here's a quick how-to guide. Nothing ever does. Well, there isn't any third rule, but things usually come in threes. Sometimes these are combined.
Macintoshes often combine the system unit and the monitor.
Some setups have everything on one switch, etc. Figure it out. If you have speakers , they usually have to be turned on also. This takes a few moments or a few minutes , depending on your computer. During the boot-up, the system gathers all the instructions it needs from its own storage system in order to get started.