How can I set up more fans in my case if my motherboard has only 3 fan plug ins?

Any ideas?

Use a molex to 3 pin converter, hook them into the psu.

I would find a nicer one then this, but its all the search function came up with for me.

So will the fans run at their highest speed? Also is there some way to control their speeds?

you could try one of these

Yeah, if you want to control the speeds, and dont have enough fan headers. You need a fan controller. I find mechanical ones tend to work the most efficently. (I realize this is out of stock, but just to give an idea).

Generally stay away from these kind:

They are flashy, but are slow to operate. The one I had couldnt remember what I set the fans before shutdown, so they were always on high.

Thanks, also is there fan mount filters you can install on you kase so that your not blowing dust on your case. My case is a corsair 200r.

I would just cover it with some thin mesh from the local hardware store. Can use filters for furnaces and things.

If you want to avoid dealing with a fan controller, you could pick up some of these Antec fans:

I personally love them.  But then again I don't see a need to adjust them on-the-fly anyway.  If you want to be adjusting their speeds frequently, then yeah stick to a fan controller