Just change the boot device in Bios. When start up keep pressing del. One's you see the screen search for the option to change the boot device. Just don't change anything else and you shut be fine. Its not rocket science at all. As long you don't change anything else then the boot device you will be fine man.
The best way to learn it is to do it. Fuck the people who are little pussy's and say, no no no don't go there if you don't know what you are doing.
How do you think other people have learn how to do it? Exactly, just by doing it. If you are unsure, go to youtube and type in change boot device in bios and there's a ton of video's show you what to do, and what not to do.