First, read through the stickies above the posts to start with, and then we have a few other places where 'literature' can be found that will save you much grief and gnashing of teeth over the upcoming moths/years
Another good place to start your journey is www.evergreengardenworks.com/articles.htm though much may be over your head, it will all come together as you grasp each snmall concept and build upon it...one step at a time...
Things we *will* need are species (or name of type of tree, even a fair descrip if not available so we can suggest pics to look at for ID purposes; evergreen-v-deciduous, blah, blah), type soil within pot, last time repotted (if known), and stuff like that. All this is really easy, but you must forget all that you have learned about 'houseplants' very quickly. Big difference, and we're here for ya
Get back with us soon, OK?
And *any* pic, even cruddy cell phone pic(s) is worth is weight in gold, so to speak...
Do NOT water/mist, or otherwise make it 'wetter' everyday unless soil dries daily
(big thing there) and do not fertilize it at all for now. Kinda just let it be for now, and keep it still (ie - no moving it around to show off to everyone or such, OK?) These are just a few of the most-common beginner's mistakes, hence my mentioning, not accusatory towards *you* at all
And ken is very much correct that is very normal for a 'relocated' tree to shed some leaves, sometimes to point of *all* leaves being lost in extreme cases. Don't freak, OK...we'll get ya set nicely as soon as you can get us more details. Myself, I will be back around here a bit later today...