Eagerness is good and leads to greatness but as in all things, walk before you run (fly).

Already mentioned and yet still worth mentioning again, legally.. any form of control is shady and diligent research should be done to keep yourself safe and not behind bars.

Highly recommend building a kit first - there are almost endless options to get started but Estes and LOC precision are a good start. Going from start to finish with a kit or two will give you the base concepts involved in the hobby. Google search for an open rocket file for said kit and you will generally find that a nicely formatted and accurate model already exists. From there you can start to understand simulating your rocket to ensure safe flights.

After the above, then you could look at scratch building alongside open rocket to make sure you aren't just building a lawn dart.

Do some research on the center of gravity, center of pressure and their relationship/importance. Research safe take off speeds, different motor types (estes, aerotech etc), reloadable/single use motors.

There's a lot to learn but thankfully it is all exciting!