Getting a grip on boxes

So when I first started skiing park there were just a couple rails on my mountain and no boxes, so I learned on the rails, once I realized how much fun park was, I set up a couple of pvc pipes in the back yard and since then I've learned front and back 270s and switch ups on rails. But now, my mountain got rid or there rails because "they are too dangerous" and just have boxes. But for the life of me I can't grip the boxes to spin or just pop off of a normal railslide. It's really fucking frustrating to have gone back to looking like a total newb again, so please share any tips or advice.