Often times one tries to trade off the oppenents light squared bishop for control of the light squares, and the dark bishop for the dark square control.

Question is: What does control over the light or dark squares mean? What should the strategy be after such trades? (ie Knight for Bishop or Bishop for bishop)

Does it mean placing your pawns/pieces on the color squares you are trying to take control or does it mean having your pawns/peices attacking the colored squares? 

any help is greatly apprieciated. Somewhat stupid question but thanks.

It's not a stupid question at all... it is a really big question though.

You're also mixing up two topics...

Topic 1 is "bad bishops" -- friendly pawns interfere with the mobility of the bishop of the same color. So for example, If you have just a dark square bishop, you want your pawns on the light squares (in general... there are plenty of exceptions). This is most true when you are in an ending with same color bishops. Say both sides have DSBs and pawns... if your pawns are on the light squares, then your bishop moves around unimpeded by friendly pawns AND your pawns are immune from attack (he's got a DSB too, so he can't touch your pawns  except with his king.) Meanwhile the enemy has his pawns on the Dark Squares.. his pawns are in the way of his Bishop AND are targets for your Bishop... many many games have been won on the basis of this simple, but crucial, difference in pawns.

Topic 2. Color complexes. Very often a player will have many of his pieces and pawns operating on one color, leaving him strong on that color, but weak on the opposite color... if you keep your eyes open you will see that time and time again, a winning attack occurs because although it looks, at first glance, like the defender has plenty of defensive resources, the defender is postioned to protect light squares and the attack is happening on the dark squares and the defender is helpless. I don't want to lecture on this topic since I'm just learning this myself

ok thank you.

question: so does controlling light or dark squares mean that your peices are on that color or that your peices are attacking that color?

controlling dark squares generally mean your pieces are attacking that colour, and

if your pieces are attacking that colour AND are on that coloured squares as well, you're dominating that colour complex.

though i think this topic is too complicated for most of us non-masters and also we'll problably never get to use it...

 I am no master and use it all the time(subconsciously for the most part).

Generally controlling a square means your pieces are attacking that square(of course there does not necessarily have to be material on the square).  You can also control a square by blockade(putting a knight on a square in front of a passed pawn)This is in effect controlling the square as well

Controlling squares means attacking them (and sometimes occupying them) with your pieces. For example, if you have a fianchettoed bishop at g2, your strategy should include moves like Nc3, which attacks the white central squares, and pawn moves like c4, d3, and trying to open up the e file so you can push e5 and give your bishop free reign over the a8-h1 diagonal.