I’d have to suggest reading around in the forums and you’ll find some pretty good information. If you have any questions after that, I’m sure someone here will be able to answer them. Since I was snipped against my will when I was a baby, I no longer have a foreskin, so I’m afraid I won’t be a lot of help in that specific area.
But as far as general usage of the Stealth, once you get it, I can only suggest starting out slow, and only wear the actual sheath initially, and let your penis get used to it. It will take time to adjust, and the sheath will take some time to relax a bit, and fit comfortably. It will be tight at first, and you may see some interstitial fluid bumps forming around the glans of your penis (depending on whether you wear the sheath with the foreskin retracted or not, I suppose, but again, I can’t speak to that specific area. If the bumps form, just take off the sheath, and let your penis rest for a while (perhaps a day or two), then try again.) Wear it for short periods of time initially, until you start to get used to it. Then you can move up to longer periods of time, and perhaps add layers (they help to make it more rigid, but they also will squeeze harder on your penis, so be ready for a tighter fit. It can also make it harder to pee when wearing the Stealth, so be ready for that, too.)
Anyhoo, take it slow, and use the additional sleeves and silicone ring once your penis has adjusted to the main part of the stealth, and the additional layers.
Good luck, and happy Stealthing.