If you are starting out with a slab of beef, then you need a meatgrinder. A hand-crank that you clamp onto your kitchen counter. Or a meatgrinder attachment if you have a KitchenAid stand mixer. Or a freestanding electric grinder.
Otherwise, just BUY some ground beef at the store. I prefer the lean or exra-lean ground beef, so they won't be too greasy.
Find a recipe online. Even better yet, look for a video on YouTube that SHOWS you how to do it.
Burgers and meatballs are very easy to make, but there are many choices about what you might want to add. And how MUCH of any extra ingredient you might want to add. Spices, herbs, breadcrumbs, diced onion, Worcestershire sauce ... all SORTS of options.
I just add onions, salt and pepper ... and sometimes a bit of breadcrumbs.