You will need to say which tree you want to move Guest. As a rule of thumb trees and shrubs are moved after they have shed their leaves, if they are deciduous and any time when it is not frosty over the winter, for any tree. You cannot just lift trees and move them as you would perennial flowers. Tthey do need some forward planning. I suggest you join GOY and post a photograph of the tree if you do not know its name to get more specific information.

As Scotsgran says, plant name necessary - trees vary in size from under a foot (dwarf conifers) to 100 feet.