It is still a very open ended question. Yes, a guide could be recommended - but for what type of computer? A gaming rig? Photo editing? Web browsing and office tasks? What budget?
I would suggest you do a search on YouTube for "How To Build A PC" - you can add the type as another keyword if you have a specific need - and you will find an endless number of videos from the likes of 'Linus Tech Tips', 'IGN' , 'JayzTwoCents', etc, etc... which will walk you through assembly. Some will also explain why the varrious parts were selected.
As far as building a laptop from scratch, that doesn't really happen... you can customise one from a curated list of options, but I'm not aware of being actually able to *build* one.
I would suggest you do a search on YouTube for "How To Build A PC" - you can add the type as another keyword if you have a specific need - and you will find an endless number of videos from the likes of 'Linus Tech Tips', 'IGN' , 'JayzTwoCents', etc, etc... which will walk you through assembly. Some will also explain why the varrious parts were selected.
As far as building a laptop from scratch, that doesn't really happen... you can customise one from a curated list of options, but I'm not aware of being actually able to *build* one.