Well Ron, typically you level initially the side to side aspect first by using blocks under the tires on the low side or some even dig holes under the high side. Be careful with cinder block as they aren't really designed for this type of use (they get their strength from being filled with concrete). I always used 2x6's or wider and always made sure that what I did with one tire on a side, I also did to the tandem tire on the same side.
Then, once you have the side to side level, then you use the tongue jack to level front to rear. Once you have that set up where you want it, then screw down the stabilizer jacks on all four corners and cinch them up tight. DO NOT use the stabilizer jacks to level with as you will probably screw up the threads.
You will still have movement throughout the trailer as most of the weight is still on the tires and suspension. There are different devices you can purchase to help reduce this movement, but you'll never get rid of it completely unless you take all the weight off of the tires.
Hope this helps
Ron