Hey John,
to buy a CNC machine takes one minute. Choosing one maybe one month of research. But if you don’t want to stay with making name signs for the thanksgiving table (which would not justify the costs of such a machine), you need to master a CAD/CAM software. This means virtual 3D objects creation. To master such a software takes at least about one year. Better three. In my country, this is a profession which takes three years to learn.
And no, you don’t pick it up. You need to follow tutorials for monthes, be they in written form, as videos or in courses in a classroom. Otherwise your knowledge and capabilities to make something with such a machine will remain rudimentary and unsatisfactory, often leading to the question if space in the garage could be used in a better way. Many believed they could pick the knowledge up, you see their machines ending in the “for sale” section.
See also
Welcome to the forum!