Setting up scope, utilizing parrallax?

I bought an FX 6-24x44 scope. It has a side turret for parrallax.

when setting up the scope and centering it say at possibly 15 yards near and 35 yards far how or what value to I set the parrallax to?

Its goingon an FX wildcat 22. Is that a good range to site in?

is this an adjustment that will be adjusted at all different ranges?
 
The parallax is something that effects how in or out of focus an object is. Something that's in focus at 20 yards will be blurry at 100 yards. You have to turn the parallax knob to make the image be in focus. This do not effect the point of aim or anything on the scope other than focus. 

For sighting in I usually have to go to about 10 yards to get an idea where it's shooting then I'll go out to about 30 yards to zero it. You'll want to zero the wildcat near the distance that you will be doing most of your shooting.
 
You do not set the parallax knob by the numbers. You look through the scope at your current target and adjust the parallax knob until both reticle and target is in focus. If you have adjusted the eye piece properly you should be able to move your head around (without moving the scope or gun) without the reticle moving around the target. If the gun is stationary you can easily check this and adjust parallax until the crosshair remains stationary on the target no matter how you move your head. It is now parallax free and ready to shoot. (but like I said, with a scope set up for your eye it should be enough to make sure both reticle and target is focused and clear)