Carpentry is a great skill to learn. Observe carpenters at work, and read “how to do it” websites. This will show you the basics.
Accumulate some hand tools, and a good tool bag or apron. Always remember, “safety first”. Look for apprentice or helper jobs, what you learn will be invaluable. Carpentry encompasses framing, concrete forms, roofing, siding, sheetrocking, finish carpentry – you have a lot of choices for your “niche”.
I found this book indispensable, and keep a copy around so the ideas are fresh, especially on layout and project planning:
Consider going to a school, or joining an apprenticeship program.
This is one run by a community college in the US: Registered Apprenticeships
This is a good guide to keep in your toolbox:
Keep in mind that carpentry is a craft that takes years of work and practice to master, learn all you can, and you will do famously well!
Best of luck with your Carpentry projects! Post pictures of your work so we can enjoy it too! -Alan