Without some practice and skills, that handle you drew will be hard to fit on the nakago ( tang).
I would do one of three things on a first knife:
1) Make the handle a full tang type. It will be much easier to fit than trying to hollow out the seat and have very thin sides.
2) Make the handle a paracord wrap style. This goes well on a tanto style, and is easy to do. You can wrap ir a dozen times if needed until you get what you want. Once it is right, just apply a light soak of epoxy and the handle is permanent. Read up on "paracord wrapped handle", "cord wrapping", and similar searches.
3) Make the tang a normal stick tang and do a normal hidden tang handle construction. This is also the easiest choice.
If that is just a ricasso in the drawing, it will be no problem to do. Some people call a solid ricasso made to look like a habaki a "faux habaki".
If it is a habaki ( blade collar) then you will need the skills and tools to make one. It isn't hard with the right tools, but it isn't a beginner project.
If you decide to make a hidden tang handle ( best idea), or even a full tang, here is a trick for getting it perfectly shaped and sanded:
Fitting the handle up against the tsuba ( guard) on any knife can be difficult. It is hard not to scratch up the guard, and the handle almost always is poorly shaped where the two meet. The trick is to make and fit the guard, and then set it aside. Make a second guard out of masonite. Micarta, or wood. It does not need to be shaped like the guard, just fitted to the tang right now. It does need to be the same thickness as the guard, or a tad less ( but no more). Place the "work guard" on the knife and fit the handle block to the tang. Once it is fitted, and any holes are drilled, start shaping it. You can wedge a few strips of paper in the guard slot to hold the handle in place, but what I do is make a temporary wooden pin ( mekugi) for the handle and put it in where the pin(s)/rivet(s) will be. This keeps the handle and guard snug and allows shaping of the handle. Just shape the work guard piece to match the handle...don't have it stick out any. This allows the handle to be fully shaped and sanded until it is done. If applying a finish, you can do that now, too. Once the handle is done as much as you want. Carefully knock out the wooden pins. If they won't come out because of the finish making them stuck, carefully drill them out with a drill bit or Dremel tool burr. Remove the handle and place the real guard on the knife. Put on the handle and check the fit and alignment of the pin hole(s). If all is well, you can glue up the handle, install the pins, rivets and finish the knife. If the handle is a tad too snug, carefully file the end to make the pins align with the holes. If it is too loose, make a thin copper (or other material) spacer to go between the handle and the guard. This spacer is called a seppa.