There are many different types of chisels that you can use for woodworking. One of the best sets to get as a beginner, though, are these bench chisels. Sometimes they're called beveled edge firmer chisels.
And, what these are used for, many different tasks. Everything from raw hand tool work, to cleaning out machine joints.
The first step is flattening the back. So, much like we have to do with hand planes on the bottom of their sole, we also have to flatten the back of chisels. Sometimes they'll be concave. Or, they'll just have machine marks from the factory. And, the goal is to get them as flat as possible, almost to a high polish, like these ones are.
And, you can use high grit sandpaper. Going through grits. This is a method that works really well for me. I have boards set up with different grits of sandpaper on these pieces of flow glass. And, I'll just rub the backs of the chisels successively on those different grits until you get up to about 2000 grit.
Once the back is flat, you'll have to sharpen the edge, the front edge. And, there's many different ways to do this. Most woodworkers use grinders. And, it gives a hollow ground front edge on the chisel.
That establishes the shape of the front. But, then you also need to hone that edge using finer grits of either sandpaper in that method I just showed you for lapping the back. Or, you can use water stones or oil stones, of course. Those are the traditional methods.
Those require some skill in keeping the correct angle. Now, most bench chisels are sharpened to 30, 35 degrees.
And, so establishing that angle on the front, and keeping it there as you're sharpening, is one of the real tough skills, I think, to learn in woodworking. But, it's well worth it. If you can get your hand control tipped down like that then you're way ahead of the game.