kobiet, kobiety, kobieta...when do I use them?
One of the main structural principles in Polish is the same as in lots of other languages (German, Greek, Latin, Russian, lots more ...). It is really important to grasp, because we hardly play around with nouns in English, but nouns have lots of different forms in Polish and these other languages.
Basically, in English you have:
dog
dog's
dogs
- and those are your three noun forms.
In Polish, for starters you have a different form for each of these contexts (PLEASE NOTE: THE POLISH UNDERNEATH IS A JOKE):
The DOG went for a walk.
Dog poszedl na spacer ...
The bicycle ran over the DOG.
Rower rozjechal Doga ...
The boy stood on the DOG'S tail.
Chlopiec stal na ogonka Doga ...
Tell the DOG all about it.
Powiedz Dogowy o tym wszystkim ...
I am thinking about the DOG.
Mysle, o Doga ...
I am a DOG.
Jestem Dogem.
Hey, DOG!
Hej, Dogu!
... and then the same again for the plural.
You might think this makes life difficult, but actually it defines life and action in a more precise way than English, and as such is rather satisfying, I find.
And yes, words which describe the nouns (adjectives, numbers, etc.) do have to follow suit, as it were.
My advice: grasp the principles, then learn actual words and how they go in small, simple steps.
Good luck ...