I can see what you are asking but there is not really an answer to your question.
That isn't helpful, so I will explain a bit.
You are 100% right the c and f pawns are often excellent tool to fight for control of the center.
Where white opens with 1 d4, N f3 or c4 the c pawn usually goes to c4 often occampanied by and early d4. The strategy in the queens gambit for white is to challenge black's center immediately with 2c4.
Whites strategy in the Kings Gambit is also to challenge black's center immediately. But this really is a gambit and f4 weakens whites own king position, so its a riskier and less popular opening.
There are openings where white plays all of c4, d4, f4 and e4 early. The 4 pawns attack in the kings indian and the advance variation in the alekhines defence for example. This creates a massive center early, but involves a lot of pawn moves, so white may well be behind in development and that center muct be protected. So its an agressive double edged strategy.
Now your question seems to be about white in a position like-
1e4 d6
2 d4 Nf6
3 Nc3 g6
4 Nf3 Bg7
But this can arise in many different forms and openings. If you don't know the exact or even approximate position nobody can say where you should move a N to free up a c or f pawn. The right move in one position will be wrong or illegal in others.
Has anyone here ever wondered that maybe if the c and f pawns were able to press forward with your d and e pawns that you would be able to get a better and good attacking force? But it's to my utter understanding that getting your knights out and into play that that's a good thing. But what are you suppose to do once you've DONE that and end up blocking those c and f pawns?? I think they would be good if they were open to play; to play on the-side kind of thing to support your e and d pawn (if your lucky enough to have both those pawns up two spaces in the begining, or even one of them)
My question to all of you is, in your past games, where have your knights gone to allow the pawns behind them to move forward? Is there some strategy that you must follow so everything flows smoothly? I hate getting cramped and then those c and f pawns are useless if you can't get your knights out to another position. Can an experianced player tell me which squares to look out for so I can press my knights forward please? I don't want to move it to just any square. But a good square. Something that is better than having "that" knight staying on f3 and c3 (or f6 and c6 if your black)
Can someone give me examples of the kind of oppurtunities one should look out for to move his knights to different squares? Squares that will be safe for the knights to give the c and f pawns some space to move forward? I know that moving your knights behind the pawns depending on the game itself is sometimes a possibility and PERFECTLY acceptable. I'm sorry if my question seems a bit confusing to answer or understand. I just thought that if I could get an example or two of how a good opening should play out, at least in the beginning.......that I could really have "a grasp" of things ;) So my game could improve :)
Many thanks to you all :)