I'm a student in high school, so please imagine you're talking to a toddler first, and second where would you advise I look for good documentation and guidance in jet engine design and tools to familiarize with.
1$\begingroup$ Not me, but I knew several mechanical engineering students at university who did a (simplified) jet engine design project as part of their bachelor's degrees. Purely a paper exercise of course; but it involved such things as designing blade profiles and various aspects of mechanical design. So I'd suggest searching for course work and text books aimed at undergraduate university students at first. $\endgroup$– AndyJul 12, 2016 at 15:45
1$\begingroup$ The book (Turns, 2006) that came with a Thermodynamics course I took, contains a nice chapter on jet engines. I guess a single book like that will easily keep you entertained for a few months, equally so for each different aspect as mentioned by @Andy. $\endgroup$– SanchisesJul 12, 2016 at 15:54
2$\begingroup$ If this question were reworded a bit to be more like this one, or this one, it would be a better question. The format of this site is a bit better for "what are good resources" than "where did you learn". $\endgroup$– foootJul 12, 2016 at 15:56
2$\begingroup$ Actually, my book suggestion got me thinking: why don't you just contact the nearest university that has an aerospace engineering faculty, and ask them which course books they use in their first year; they will probably be readily available second-hand near you. $\endgroup$– SanchisesJul 12, 2016 at 16:06
That one depends on a lot of things. Real jet engine design is going to require an understanding of advanced physics, computational fluid dynamics, thermodynamics, heat transfer, and metallurgy. It will also require college level engineering coursework as well as at least calculus and in some cases partial differential equations on order to properly design such an artifact.
Not to be deterred, amateur jet engine builders have constructed self sustaining gas turbines using old turbochargers and a custom built isobaric combustion chamber as this YouTube video shows. Both the reactive thrust and/or mechanical power one can get out of such a device is limited.
There are some existing plans available on the market for building small jet engines as this Instructables shows.
RC Aircraft modellers can also buy small scale turbine engines for around \$3,000-$5,000, depending on manufacturer, type, thrust output, etc.
Designing a proper jet engine from scratch is going to be much more difficult, though it is possible. It will be expensive and time consuming, but if you really want to learn the art of building turbine engines, it's possible. I would advise waiting until college and pursuing a degree in aerospace engineering. The major aero schools (e.g. Michigan, Purdue, MIT, CalTech, etc. all have extra curricular clubs as well as design and testing facilities and equipment for this sort of stuff and as I said before you will need higher level engineering and mathematics education in order to do it right. That's not to say this is impossible; the Rocket Boys, a pack of coal miner's sons whom the film October Sky was based upon, were designing Di Laval nozzles using differential equations in high school, so if you really want to learn, it's always possible, though not always easy.
If you do want to start down that path and want a challenge, I'd recommend The Design of High Efficiency Turbomachinery and Gas Turbines by Wilson and Korakianitis. I'd also recommend primers on thermodynamics and heat transfer as well.
You might attempt the earlier turbocharger projects first or disassemble an RC jet engine to get a much better familiarization first, then attempt the engineering of an engine from scratch.
In addition, seek out other jet engine builders and talk with them. They will be a wealth of information for you at the beginning of the project.
You might also seek out professors at a good aerospace engineering program somewhere and ask them what direction they would recommend you to begin such a project. Remember: Old people find nothing more flattering than a youngster who will sit patiently and listen to what they do for a living; employ that to your advantage.
A long shot but it might work as well - get involved with Linkedin and look for profiles of engineers who are employed at places like UTC/Pratt & Whitney, GE Aircraft Engines, Rolls Royce, Eurojet, etc. You might just find someone there who designs jet engine parts for a living and can be a good resource.
Also, as with any kind of engineering or programming, start simple and work up to complex. Your not just building an artifact, you're building a database of knowledge of how to build such an artifact as well, which can be built upon in increasingly more complex designs.
Oh, and one final caution: gas turbines belch large, noisy quantities of high temperature, high pressure gas and operate at very high temps, creating the possibility of serious injury, explosions and/or fire hazards. Approach the design and testing process with caution and take appropriate safety measures i.e. don't test this thing in your parent's basement, etc.