Hey Dino...I have to agree with all the above posts. YouTube has an awesome wealth of info. RC forums are a huge asset. This forum, in particular, has dozens of helicopter pilots and, from what I can tell (4 years on this forum), everyone here is always willing to lend a hand and give info. No one here knows it all but, as whole, this forum is amazing!!!
Matthias also has a good point. Building a new heli kit is an awesome way to learn how things go together, but you did mention that you are now retired and you don't have a large disposable income. So, a used helicopter may be a better way to go. Do you have your own helicopter(s)? Do you have a manual(s)? Taking a helicopter apart and putting it back together may be a good idea....with the manual handy, of course. If you don't wanna take a helicopter apart right now, no worries....just holler at us when you have a specific question(s).
Something else you may consider, when you get done reading this....go grab some coffee and cookies....then get on YouTube and just search out "rc helicopter build". There are many many videos of helicopter builds and many of them are broken down into "parts". This way, you can see whats going on. If you have a specific helicopter, you may try doing a search for your specific helicopter and add the word "build" and see if there are any build videos for your helicopter.
In the end...just remember that we'll be here to help out!
Best of luck in your retirement, buddy!!!