First, find an ASA sailing school and take the beginning sailing courses. Learn to sail.
Then, buy books and spend a year reading and getting over the romantic vision presented by Youtube's perfect 10 sailor gal and her mustachioed sidekick. Then, look into your first boat.
That boat for example is located in an expensive foreign port, is nearing 40 years old, and needs what could very well be a 6-figure refit. There isn't even an engine installed, and the rigging and possibly spars need replacement. Even if the engine the owner says he's found is brand new and amazing, paying BVI prices to have it installed will set you back many thousands all by itself. To say nothing the rest of the systems. Judging by the panel, I'm betting the electrical system is a nightmare as well. Almost always the case on these boats. Old boats are fine if you want to tie up in the marina and start doing a refit, maybe even get your feet wet with living aboard as you work (or maybe you're rich and can just kick back and start writing large checks)...but a massive, full keeled, blue water ketch is not
what you want to learn how to sail on. That boat is going to be nearly 30,000 lbs, and will not
be easily maneuvered, docked, etc., or well sailed in light winds. It would do well offshore in a breeze, I bet, but the rest of the time...rough for a beginner. Real rough.
Take classes. Read books. See if it's for you before you get under a big old boat and an expensive refit.