Just explore a bit and you will eventually bump into a rabit, buy hunting, stand as close as you can next to the rabit, then right click it. Make sure you have 4 empty inventory spaces in a square form.
If you see a boar or bear, you will have to make sure you don't come to close as they will attack you immediately. If you find a fox/deer/auroch/mouflon they won't attack you, unless you attack them.
To attack those last animals, you should first read a guide about combat first as it is pretty difficult to understand if you're new.