Is there a book you can buy that teaches you how to buy a bike, and what size forks work with what size frames, etc... I'm looking to build one for a hobby just buying the parts as I can/need.

Not that I am aware of, at least not one that is current. I did write a proposal for such a book though:

https://gennick.com/ExampleProposal.html

I wrote the proposal as an example for use in my day-job as a computer-book editor, and chose building as the topic too keep the proposal fun and hopefully make the outline one that anyone could easily follow regardless of their technology background.

It'd be fun to actually write the book that I've outlined. Someday I might have a go at it.

BTW, building is fun. I enjoy it very much. I try to do one new build each season. Often I just buy a frame and move parts over, or rebuild an existing frame using a different set of parts. Either way gets me something different to ride, for a nice change of pace.

Use these forums as a resource. People are usually glad to answer questions.

You can start a library of various books on many cycling topics,
shop manuals ? Sutherland's, Barnett's . professional reference tools
+ there's lots of Magazines to read , maybe back issues in the Public Library?

This one even has bible in the title...https://www.amazon.com/Sloanes-Comple...7158865&sr=8-1

Seriously, I've checked out the Eugene Sloane books at just about every library I've lived near. They're old at this point, but great reading. When I first got into bikes, they were informative... even if dated.

Barnetts and Sutherlands are as close to "bible" status as it gets but they are aimed at professional shop mechanics who will have to deal with every type of bike and component and are expensive and, probably, unnecessarily detailed. The Park Tools Blue Book and Lennard Zinn's "Zinn And The Art of Road (or Mountain) Bike Maintenance" are good with as much detail as you are likely to need.

Sheldon Brown's website.

The books and sites listed above are great resources, but in all honesty you're going about this backwards. It's 10x easier to start with a complete bicycle, get out the manuals/pages printed from the web, and pay close attention as you are disassembling. Start with a "good" thrift store find (ie. not a department store level bike) for ~$35 and go to work.

Park Tool website and Youtube?

I strongly recommend Frank Berto's "Upgrading Your Bike". It is available very cheap at sites like Abe Books. it was written near the end of the pre-brighter era.