Only work on watches yourself if you have the correct tools and some experience. And guts….! When you have doubts, don’t do it, but search for a professional that also likes modding watches. You can always send the watch to me, I do this kind of operations every day and I have made special tools for it.

After opening the case back, press there to release the crown.
I usually put my tweezers there and flip out the movement
At the 12 and the 6 position, there is a recess in the bezel where to put your case-knife
If you only install a fluted bezel, you can leave the glass on the soft gasket
Bezel away
Here you can see the recess in the bezel, originally on the 12 and 6 position. I advise to put it back like that so you remember the recess-locations.
The soft gasket, it lies in a small ditch and the glass lies on it. The bezel clicks into the case and keeps all in place.
Take care the glass/sapphire is well centered, else the bezel will not close correctly.
Put the bezel back, recess positioned back at 6 and 12.
Press on the bezel (I have a stamp that only presses on the sides and not in the middle), usually you will hear a click.
After cleaning the inside it is ready for re-installing the inides.