To add to what HillBill said, if it is a new knife meant for bush survival and you want to change or thin the bevel it is likely to take a very very long time as they have robust bevels cut in them from the factory that are often quite obtuse.
Whet stone simply means sharpening stone. As was said above there are many different types. Diamonds, waterstones both synthetic and natural, so called oil stones which can be used with water if you boil the oil out of them, natural stones from a variety of countries such as Arkansas stones and Couticles which can both be used with water. As was said above, some types of stones only come in coarser grits whereas others come in finer grits. Lets take a look.
Diamond stones come in a range of 120-9 micron. If we keep this on the Japanses scale that is about 120-1500 grit. Such stones will sharpen anything you throw at them but will remove a lot of metal fast if you are not careful.
Oil stones such as Norton India stones are quite fast as well and will sharpen most things but they only come in at about 100-400 grit on the Japanese scale. Their main advantage is that they are dirt cheap and simply work.
Ceramic stones such as Spyderco come in a range of medium-fine. Once again on a Japanese scale of about 1500-6000. They are not cheap and load with swarf quickly meaning that you will have to clean them frequently for them to continue cutting. They do work well though.
Japanese synthetic waterstones I have seen range from 24-30000 grit. Something like 400-0.5 microns. These stones vary greatly in their makeup and price. From chalk soft to ceramic hard. They require flattening with a diamond plate or some other medium. They can be slower or faster but always slower than diamonds and always faster than natural stones.
Japanese naturals is where you start opening a can of worms and is something best left until one gets loads of experience as they can be very slow and extremely expensive. They don't have to be but it is harder to source what you want from a reputable dealer.
Natural stones such as Arkansas are medium priced and slow as molasses. That is to say they work wonders on typical bushcraft knives with basic carbon steel blades or knives of yesteryear such as Green river and Old Hickory. In terms of Japanese grit they fall into the medium category about 1000-4000 grit.
As for thinning the bevel it is a simple but lengthy process. Lay the knife on the stone and push forward while slowly rasing the angle once the edge bites into the stone you are at the apex, lower it about 3-4 degrees and sharpen until you have a bur, flip the knife and go again. This will effectively thin the knife. If you want it thinner just use it until dull and sharpen while thinning again. Eventually you will naturally thin the knife. Are there other means, sure there are but they are time consuming and once again as was previously mentioned often times better left to the professionals or enthusiasts.
One last thing, if your stones are coarse grit stones, be careful as they can and will remove metal faster than you think.
Good luck and have fun.
PS: If you can't tell, I am addicted to whetstone sharpening.