You can move a box by stepping in front of the box and pressing the 'spacebar' key (or 'Use' - for the PSX, you press the Triangle key, I believe). Then, either press forward or backward, and you'll move the box in that direction.
If you're having trouble, there is a pretty good online game guide available at:
http://www.gamespot.com/features/tpm_gg/index.html)
I don't know from your post whether you have the PC or Playstation version. This game guide will work for both; the only difference between PC and PSX versions occurs on the final level. We were forced to change 2 puzzles because the PSX version couldn't handle some goofy things we were doing with pushblocks. Once you get to the Final Battle level and find the PC guide lacking, let us know here and I'll help you out
http://www.jediknight.net/mboard/wink.gif)
[This message has been edited by Zanzibar (edited May 01, 2000).]