Try this:

Select your first box at frame 0 and hit "s" to key it in the start position. Then move the time slider forward, move the box, and hit "s" again.

Then, go back to frame 0 and select the second box. Hit "s" to key its start position. Move the slider, move it to its new position, then hit "s" again.

You need to key the first frame too, to set the start position. Once you get this principle, you can set frames in between frame 0 and the later frames, to make the box stay where it is, change its course or speed etc.

Hope this helps.

cheers,

gubar.